The ink had not even dried on the signing of the Paris Accord before it was subverted by the American imperialists and their puppet Saigon regime. In the days following the signing of the Paris Accord, the sounds of gunfire continued to explode over the Southern theater. With American aid, the puppet Saigon regime made every effort to build the puppet army, continued to carry on the war, and launched "flood the territory" operations to pacify and occupy our liberated regions.
Confronted by the schemes and operations of the enemy, the Central Military Committee instructed the armed forces in the South:
We must seize on the strategy of attack, defeating each of the enemy's pacification/occupation operations, winning the people and keeping the people, holding on to the liberated regions and revolutionary authority. At the same time, we must be ready for every contingency; if the enemy expands the war to provoke larger scale warfare, then we must be determined to exterminate them.[94]
Thoroughly, profoundly, grasping Resolution 21 of the Central Party Executive Committee and the resolution of the Central Military Committee, based upon an accurate appreciation of the mission situation, the cryptographic cadre and personnel clearly determined the political responsibility, and, with revolutionary ardor reinforcing combat will, concentrated on doing their utmost to carry out the specialty missions.
By 1972, because of the complicated situation after the signing of the Paris Accords, the volume of messages which the cryptographic organizations had to take care of continued to be very large. According to incomplete statistics, in the military cryptographic system of the South, for the first six months of 1973, the number of messages sent and received must be reckoned at 632,336 official messages.
In MR 9, the enemy continued to mount operations up to division level, to occupy our liberated regions. Cryptographic organizations did a good job serving MR HQ commanding counterattacks and attacks on the enemy, to hold on to the liberated regions. In March 1973, four comrades from the MR Cryptographic Section continuously decrypted 295 Immediate [tôi khân] messages in the KTC technique, containing the Central Military Committee resolution, while the MR committee met, waiting for the contents of this resolution. Afterward, eight comrades encrypted and decrypted continuously 1,460 Priority official messages in two consecutive days, in order to get them promptly to the command comrades.
At the beginning of 1973, a joint [lien hiêp] military cryptographic organization was established to serve command leadership and warfare guidance with the enemy in the implementation of the Paris Accords. Four hundred thirty-two army cryptographic cadre and personnel were assembled and stationed in forty cryptographic organizations, comprising the Northern Military Delegation, the Southern Military Delegation B, seven regions, and 30 [control] teams. The liaison network for cryptographic technique was also organized, ensuring thorough grasp from the outset. When they came into contact with the enemy, cryptographic cadre and personnel in the groups and teams comported themselves with the bearing of victors. The comrades were very cool and vigilant in the face of each of the enemy's actions and provocative tricks. There were comrades whom the enemy tried to rob of their technical material pouches, but the comrades had such a determined attitude that the enemy had to back off.
In MR 5, during 1973, the enemy mopped up and occupied on a large scale. The MR cryptographic organization alternated between performing the mission of ensuring service to leadership and combat command in striking the enemy, and in ensuring service to the joint [lien hop] commissions and teams. Joint commissions of the Sector, Region 2, Region 3, the joint teams of nine provinces and cities were in liaison with HQ and the Four-Party Joint Military Commission at Tan Son Nhat. In order to overcome the lack of troop strength, the MR 5 Cryptographic Bureau realigned forces and urgently enrolled students for quick training in order to have personnel to augment the places that were lacking and [still] have forces in reserve. At the same time, the Cryptographic Bureau also organized cadre refresher classes to upgrade their technical level – the volume encrypted and decrypted and sent, using technique KTC – for a number of cryptographic personnel from division and provincial unit levels.
Day and night the Bureau of Encrypting and Decrypting of the General Staff Cryptographic Directorate served to ensure leadership and command from HQ to the theaters of war. The bureau also assigned ten cadre and personnel to go serve the Two-Party and Four-Party Joint Military Commissions and established an encryption-decryption section responsible for the liaison net system for guidance in the implementation of the Paris accord. This was a time in which the message volume the bureau had to handle increased manyfold. The volume of messages to encrypt and decrypt on some days went up to 1,000 official messages. The total number of messages handled by the bureau in 1973 was 205,992 official messages comprising 12,264,222 groups.
In October 1973, I Corps [quân đoàn] was formed. Along with the formation of the corps, the cryptographic organization took shape, comprising the corps Cryptographic Bureau, the Cryptographic Sections of the 308th, 312th, 320th, and 367th divisions, the cryptographic organizations of the 45th, 202nd, and 299th brigades, the cryptographic teams at battalion level, etc. Comrade Nguyen Quoc Sung was appointed chief of the corps cryptographic bureau. The Cryptographic Directorate of the General Staff guided and assisted the I Corps cryptographic organization to quickly settle its organization; urgently get into implementation, as an orderly routine, of the tasks of serving to ensure command; training; and the other aspects of the professional task, in order to do a good job from the outset of implementing the mission of the cryptographic organization in the first corps of our army. Also in 1973 the system of cryptographic organization expanded into the MRs, services, and branches, i.e., establishing the Cryptographic Section of the 919th Air Force Transport Brigade, the Cryptographic Section of the 673rd Air Defense Division, etc.
Working while building, in every aspect, cryptographic organizations army-wide stepped up their study and raised productivity and quality in the use of technique KTC. By the end of 1973, the cryptographic organizations in MR Viet Bac, MR Northwest, MR Left Bank, MR IV, the Naval Service, a number of divisions belonging to the Air Defense-Air Force Service, and Armor HQ had stopped using KTB5 and changed over to technique KTC5. The cryptographic organizations of the 320B Division, 304th Division, and 320th Division began to expand the study and use of KTC. Cryptographic organizations in MR 5, the Highlands Front, and in Nam Bo also expanded the training and use of technique KTC down to basic units, with a sense of immediacy and zealousness.
The Cryptographic Directorate of the General Staff summarized and disseminated the concrete experiences concerning the tasks of organization, training, and use of KTC, especially the experience of training in the basic technical subjects of encrypting and decrypting, helping cryptographic organizations at various levels army-wide to achieve good results.
In the movement to study the use of KTC bubbling through the entire army, there were many units and individuals who achieved rather high productivity and volume. The Encrypting-Decrypting Bureau of the General Staff Cryptographic Directorate achieved an average productivity in encrypting and decrypting of 542 groups per hour, with a 99.90 percent accuracy, and many comrades achieved record highs, such as Cde [Miss] Pham Thi Vien, with 750 groups per hour, Cde [Miss] Pham Thi Vien, with 740 groups per hour, etc.
During this time, many cryptographic cadre and personnel from the Southern theater came to the North for treatment of disease, convalescence, and study. On such occasions, the Cryptographic Directorate organized refresher courses in techniques and professionalism. Cryptographic organizations of the MRs, services, and branches also proceeded to organize training in the various task aspects for cadre and personnel. The Cryptographic School stepped up the training of new personnel to understand the use of both types of technique (KTB5 and KTC) in order to augment the essential theaters, principally the Southern theater.
Carrying out the instructions from the Central Cryptographic Section, the army cryptographic branch implemented a summarization of the cryptographic task in eight years of serving the resistance against America. Vis-à-vis this task, the army cryptographic organization executed it step by step, constantly and continuously, throughout the period of opposing America and saving the nation. Thanks to doing a good job of recapitulation, the army cryptographic branch promptly drew experience, publicized achievements and strong points, while, at the same time, quickly resolving shortcomings and promptly taking corrective action to get every aspect into the routine.
In 1969, after a recapitulation of the task, the MR Left Bank Cryptographic Bureau wrote two documents, "Raising Productivity and Quality of Encrypting and Decrypting to Serve Victorious Combat," and "The Independent Cryptographic Task."
Through service to the campaigns to strike the enemy and ensure lines of communication and transportation in MR 4 and the 1972 strategic general offensive campaign (for example, the task of cryptographic service in the Tri-Thien campaign and the task of serving command leadership of [Southern] Region HQ), through the periods and campaigns of defeating the American imperialists' strategic assaults by B-52s on Hanoi and Haiphong in December 1972, the bureaus of cryptography, the Encrypting-Decrypting Bureau of the General Staff Directorate of Cryptography, the [Southern] Region Cryptographic Bureau, cryptographic bureaus of the MRs, services and branches – all recapitulated and drew experience concerning the thorough grasp of mission, concerning the task of organizing technical networks [hê tôńg], implementing encryption and decryption, and ensuring the flow of outgoing and incoming messages.
During the period of resisting America's war of destruction, the Cryptographic Directorate of the General Staff collected and sorted out situations, assessments, appreciations of accomplishments, good points and bad points in implementation of the missions of the various cryptographic organizations, and extracted major experiences of value to professional leadership for the whole branch. Based upon summarization of the documentation and of the experiences, the General Staff Cryptographic Directorate compiled and produced documents that put forth reasoning and technical professional practices to nourish and elevate the specialty level of cadre and personnel, e.g., "Organization and Implementation of the Cryptographic Task of the People's Army of Viet Nam in War Time," "Message Error Detection and Prediction," "Methods of Training in the Four Primary Technical Subjects and Raising the Productivity of Double Encryption," and "The Independent Cryptographic Task."
Summarizing the eight-year national salvation struggle against America (1965–1972), the accomplishments of the army cryptographic branch that stand out greatly are having organized and done a good job of executing the task of encrypting and decrypting messages, ensuring that 50,008,006 secret messages, sent and received, were secure, accurate, and timely, not allowing error to influence the tasks of leadership, direction, and command, especially having implemented in outstanding fashion the policy of changeover to new technique under circumstances in which the task was difficult, complicated, with endless hardship and fierce fighting. After eight years of being put to the test, the army cryptographic branch had built the ranks of cadre and personnel to 5,337 comrades of good political quality, steadfast and tempered, with high revolutionary ardor, with a sense of responsibility for the political mission of the branch, and with a sense of responsibility for organization and discipline – a spirit of overcoming obstacles and withstanding hardships – sacrifice of life – diligently studying to raise the level of ability – to accomplish the mission – to be worthy of being members of the Lao Dong Party of Viet Nam. Some 450 comrades had given their lives for their country.
In March 1974, a conference was convened in Hanoi to recapitulate the cryptographic mission of eight years of service in the national salvation struggle against America (1965–1972) on the part of Viet Nam's cryptographic branch. Groups of cryptographic delegates from the networks of Party and government, army and public security, representatives of cryptographic organizations from the entire nation, and cryptographic teams on international duty came back to participate adequately. The delegation of the army cryptographic branch, led by the comrade chief of the directorate and comprising comrade representatives of the General Staff Directorate of Cryptography and representatives of the MRs, services, branches, and the unit organizations, arrived to participate in the conference.
The conference took place ebullient in the impetus of victory, with a sense of confidence and heightened unanimity. This was a conference of most important significance, for it marked the growing up of the Vietnamese cryptographic branch in the process of combat, building and expanding, in the task of ensuring leadership and command of the revolutionary war.
The conference was graced with the presence of Cde Le Duc Tho, member of the Politburo and Secretary of the Central Party and Cde Nguyen Don, member of the Central Party and Deputy Chief of the General Staff, who visited and spoke. Cde Le Duc Tho commended the accomplishments of the cryptographic branch: "We have come through eighteen years of resistance to America, saving the nation (1955–1972), and have achieved a great victory. Comrades still living as well as those who have given their lives – all have made a worthy contribution to this great victory of our race . . . Today I come to speak to you all in order to express the sentiments of the Central Party toward the cryptographic branch, toward you comrades, and also to commend you comrades who have made a worthy contribution yourselves toward the work of the Party, the work of our race in resisting America and saving the nation." After speaking clearly of the position, the role, and the concrete accomplishments of the cryptographic task, Cde Le Duc Tho continued with feeling: "Central is very pleased and very moved that you comrades have made great efforts, have given your lives. Nearly 500 cadre and personnel have fallen, a proportion that was high, for this was many, not few; this sacrifice was not less than that of soldiers on the field of battle; this sacrifice was rather large. Here, too, was a front with large casualties."[95]
The comrade thoughtfully suggested: "The victory road of revolution is indispensable – we shall absolutely liberate the South and unify the nation, but if we wish to achieve victory, we still must pass through steps on a hard and difficult road. The mission of you comrades is still very exacting – you still must plow a long way through the theaters of war, you must transmit the instructions and resolutions of the Party, and of the government, from organizations at the nerve center out to places on all three fronts – military, political, and foreign affairs . . . You comrades must study to raise the level of scientific professional technique, to raise the level – more modern, more creative. When you conclude the conference, people in this front – people in that front, people in the North, people in the South, people in foreign nations, spread out everywhere in theaters and fronts to perform the mission, although saying not a word, are quite glorious.
Cde Nguyen Don, on behalf of the Central Military Committee, congratulated the cryptographic branch for having performed its mission in an outstanding manner, through eighteen years of resistance to America and saving the nation. He analyzed deeply and concretely the achievements, good and bad points, and the reasons for these good and bad points from the organizational and technical aspects. He also clearly indicated to the cryptographic branch delegates the way for the branch to strive to advance. The delegates were moved and enthused beyond measure at the words of congratulation and counsel from the leadership comrades representing the Central Executive Committee, promising the Central Party Executive Committee and Central Military Committee that they would mobilize the cadre and personnel to do a good job of carrying out the comrades' instructions.
The conference recapitulating the cryptographic task in eight years of resistance to America and saving the nation came off beautifully. From the atmosphere of the conference was created a powerful, ebullient emulation movement in the task for the whole cryptographic branch in general and the army cryptographic branch in particular.
In May 1974, II Corps was formed, the cryptographic organization comprising the II Corps Cryptographic Bureau, the cryptographic sections of the 304th, 324th, 325th, and 673rd Divisions, and the cryptographic organizations of the 219th, 203rd, and 164th Brigades, with comrade Le Ngoc Luong chief of the Corps Cryptographic Bureau. Immediately upon the formation of the corps, the corps system of cryptography was able to ensure command service during the campaigns to liberate the district capital of Thuong Duc (Sector 5), the K18 campaign (Hue), and to serve command in preparing for battle and in the fighting against the enemy, to hold onto the Quang Tri liberated region.
In July 1974, IV Corps was formed in the Eastern Nam Bo base region. The cryptographic organization of the corps took shape, comprising the cryptographic sections of the 7th and 9th Divisions and the cryptographic organizations of the regiments and branch units.
During this time, cryptographic organizations throughout the army did a good job of accomplishing the task of encrypting and decrypting messages, serving the work of thoroughly grasping leadership and precisely implementing Central Party Resolution 21 of the Central Party and resolutions of the Central Military Committee, guiding, shaping, and molding the theaters and regions in holding fast to the viewpoint and revolutionary ideology of attack, serving to guide the building and completion of the system of strategic and campaign lines and serving command in the transportation and supply of the theaters.
The cryptographic organization in Eastern Nam Bo served command in the liberation of Phuoc Long, the first province in Nam Bo to be liberated. During this time, the Central Cryptographic Section and the Cryptographic Directorate of the General Staff zealously instructed the implementation of enrollment and development of new personnel, research into the production of various types of dictionary codes, cryptographic key, and command opcodes, according to the norm of the 1974–1975 two-year plan (which anticipated the development of 1,000 personnel, research and production of 1,500 types of dictionary codes, 3,000 sets of cryptographic key and 1,500 command opcodes). From directorate head to professional organizations, there was an increase in going to inspect and assist on the spot the cryptographic organizations throughout the army, from North to South and Laos.
From 18 December 1974 to 8 January 1975, the Politburo of Central Party met. After examining and analyzing the unfolding situation from every aspect, the Politburo resolutely determined the following strategy:
All-out mobilization of the power of the entire Party, the entire military, the entire people, in both of the two areas in 1975–1976, stepping up the military and political struggle, combined with the diplomatic struggle, to cause rapid change and across-the-board force comparison in the Southern area theater advantageous to us, implementing as a matter of urgency and accomplishing each preparatory task, creating conditions ripe for general assault, general uprising, to eliminate the puppet army and cause it to disintegrate, to strike and bring down the puppet authorities from central to regional, placing authority back in the hands of the people, and liberating the Southern area. If the opportunity arose at the beginning or end of 1975, then immediately to liberate the South in 1975.
On 10 January 1975, executing orders from the General Staff, the Cryptographic Directorate of the General Staff organized a cryptographic team of seven comrades[96] to serve Group A75 under Gen. Van Tien Dzung, chief of the General Staff, secretly going down to the Highlands in order to research, organize, and realize the Politburo's strategic decision.
The Encrypting-Decrypting Bureau of the Cryptographic Directorate of the General Staff made as its first priority the encrypting and decrypting of Group A75 messages in order to regularly serve communiques of the latest news, especially information concerning the unfolding enemy situation and the transportation situation to ensure the campaign, so that HQ could make an operations plan.
The army cryptographic branch thoroughly and profoundly grasped the important change in the revolutionary mission situation. Cryptographic organizations throughout the army enthusiastically, cheerfully, and with confidence proceeded to make preparation in every respect, so as to be ready to receive and execute the missions received from the Central Military Committee, HQ and commissars, and commanders at the various echelons.
The General Staff Cryptographic Directorate also – along with cryptographic organizations of the MRs, services, branches, etc. – researched and made concrete plans and implemented the task of supplementing, correcting, and aligning the cadre and personnel for the units, principally the main point units, with special urgency for the strategic mobile units and the key theaters.
The Army Cryptographic School picked student comrades who were coming along well and were clever, and organized them into individually assembled companies, and brought them up to speed technically and professionally in a short time, so as to have strategic reserve forces and be able to quickly assist the theaters. With an all-out effort, and after a short time, the school had prepared more than 300 comrades, ready to set out and perform the mission.
The cryptographic organizations of MR Viet Bac, MR Left Bank, MR Right Bank, etc., selected comrades of good technical ability and qualities so that, when the orders came, they could supplement and augment the forward units.
In lock step with the preparation and expansion of the organizational task, the Cryptographic Directorate issued instructions to expand the systems [hê thôhg] and means of cryptographic technique, urgently getting off a large volume of the various types of technique and professional means and equipment for the theaters. With an outstanding all-out effort, by 1 March 1975, before our army had opened fire to raise the curtain on the Spring 1975 General Offensive, cryptographic forces had expanded all over the Southern area theater as follows:
On the Highlands Front, our army opened the assault campaign under the name, "The 275 Campaign," the number of cryptographic cadre and personnel participating being 456 comrades, ensuring liaison for 374 points with seventy types of technique, the responsibility of the cryptographic organizations being to serve leadership and command of the campaign CP, the divisions, the branch units, and the main force and regional units in the Highlands area.
On the Tri-Thien-Hue Front (Front B), afterwards called the 475 Front, the cryptographic cadre and personnel resources comprised 1,144 comrades, ensuring liaison for 1,241 points, with 195 types of technique in use, the responsibility of the Tri-Thien-Hue Front cryptographic being to serve leadership and command of the Forward HQ CPs, the primary CPs, the Forward CPs of MR Tri-Thien, MR V, II Corps, the 2nd, 3rd, 324th, 325th, and 304th Divisions, the 52nd Brigade, and the branch units in the area, plus the regional units.
On the Southwest and South Saigon Front, the cryptographic cadre and personnel resources comprised 1,004 comrades along with 677 comrades of subordinate units, ensuring liaison for 1,678 points with 154 types of cryptographic technique in use. The responsibility of the cryptographic organizations of the Southwest and South Saigon Front was to serve leadership and command of Southern Area HQ; MRs 7, 8, 9; IV Corps; the branch units; the main force units in the area; and the regional units.
The cryptographic organizations of Air Defense-Air Force and Navy services and the Sapper, Armor, Engineer, and Artillery branches also developed with respect to organization and technique both widely and deeply into the Southern theaters in order to serve the duties of leadership and operational command of combined services. The Navy cryptographic network developed its campaign service duty to comprise 125 liaison points, internally, skip-echelon, direct and combined [or joint, operations]. The Air Defense cryptographic network developed at the peak time eighty-two stations, 202 points, including three forward CPs.
The cryptographic organizations in the entire army in the rear were all in the position of readiness with support people and professional technical means for the cryptographic organizations up front, in order to ensure accomplishment of the mission of the General Offensive Campaign of Spring 1975.
The total number of army cryptographic forces taking part directly in the service of the general strategic offensive and the historic Ho Chi Minh Campaign was 4,167 cadre and personnel, ensuring as a system a liaison net that, at its largest, was 3,703 places, using 419 types of cryptographic technique. Cryptographic organizations of the campaign were equipped with an additional tens of tons of professional technical means. It can be said that this was an outstanding effort on the part of the army cryptographic branch, which had never before planned to organize to ensure command leadership and operational guidance that was adequately prepared and sufficient to cover every aspect of this spring of 1975.
On 10 March 1975, the Spring 1975 general offensive and uprising opened with the daring surprise strike on the town of Ban Me Thuot. The cryptographic organizations participated in totally ensuring secrecy as to the objective of the campaign and ensuring the command secrecy of the diversionary operation of Campaign HQ (e.g., the diversionary operation of the 968th Division) to draw enemy attention to the north of the Highlands and create surprise for them when our army opened fire and struck the town of Ban Me Thuot. Dummy messages – deception messages – were continuously sent into the air on a daily basis. Military information was speedily sent back to HQ. "Every tiny movement in the theater was closely followed by the operations watch – every forward step by the troops was quickly marked on the map. The fighting in the Highlands, with Ban Me Thuot at the center, was at this time the number one concern of the Politburo and Central Military Committee – and those in charge at the General Staff and the directorates."[97]
When we victoriously assaulted the town of Ban Me Thuot, the cryptographic organization quickly passed on the contents of messages from the Politburo, Central Military Committee, axid High Command – messages for the Highlands Front, encouraging and commending the cadre and warriors, directly guiding the expansion of the campaign with the spirit of "creativity, daring, and urgency," to grasp the opportunity to secure an even greater victory. At the same time, the cryptographic organization also passed along the contents of electrical communiques for Sector 5, B2, and Tri-Thien concerning the guidelines of the upper echelons following the Ban Me Thuot victory. The Highlands Front cryptographic organization served to ensure combat command in shattering the enemy counterattack aimed at retaking Ban Me Thuot, and served to ensure command in pursuit and interception of the enemy when they fled, abandoning the Highlands and took part in exterminating and dispersing the puppet II Corps, liberating the entirety of the Highlands.
On 18 March 1975, the Politburo of the Central Party Executive Committee met. Through analyzing and estimating the situation with respect to the victory of strategic significance for our side, the Politburo and Central Military Committee unanimously resolved to produce a plan for the liberation of the Southern area in 1975, determining that the main strategic direction of attack would be Saigon, prior to which would be the extermination of all enemy forces in their MR 1 and the liberation of Hue, Da Nang, and the provinces of Central Viet Nam.
Implementing instructions from the Politburo and Central Military Committee, the General Staff prepared at once a plan for a large-scale attack to wipe out the forces in the enemy's MR 1, and to liberate Hue and Da Nang.
The General Staff cryptographic organization swiftly and precisely sent operations orders from the High Command to II Corps, MR Tri-Thien, and MR 5. "Paying no mind whether day or night, communications and cryptographic personnel assigned to duty in Sector A received and decrypted messages in a spirit of highest urgency, requiring the greatest precision, in order to keep the operations watch comrades posted, whatever the hour. The fellows and girls of communications and cryptography were educated and imbued with the degree of importance of each individual, each element, in these days and months of urgency and consecutive victories." Cryptographic organizations of II Corps and MR Tri-Thien directly passed on the command orders of the General Staff [Bo] for II Corps and MR Tri-Thien to clearly receive opportunities, grasp deep-thrust targets, and isolate, surround, and interdict the enemy's lines of withdrawal.
On 25 March 1975, Hue City and Thua Thien province were liberated.
On 25 March 1975, the Quang Da Front Command [Bô chi huy] was established under Cde Le Trong Tanas commander, Cde Chu Huy Man as political commissar, with the front cryptographic organization comprising seventy-two cadre and personnel under Cde Tran Ha.
Cryptographic organizations from the Encryption-Decryption Bureau of the General Staff down to the front cryptographic organization, and those of II Corps and MR 5 speedily set up a cryptographic technique system to serve the leadership and command guidance of HQ.
Immediately upon receiving the message of instruction from the Politburo and Central Military Committee (dated 24 March 1975, sent to MR 5 and II Corps, concerning guidelines planned for the liberation of Da Nang), the Cryptographic Bureau of MR 5 received orders from the MR to quickly develop a liaison net for HQ with direct subordinates, HQ forward, [Southern] Region Military HQ, the MR primary CP, lateral communication with the divisions of II Corps, internal liaison with the branch regiments, the primary CPs, Quang Da Forward, etc.
"Messages from the General Staff [Bô] to the Tri-Thien and Quang Da fronts were continuous, thick and furious, during these days, exuding requirements for all-out urgency, for swiftly pressing and surrounding and dispersing and wiping out the enemy in this second strategic pummeling."
The cryptographic organizations of MR 5 and 11 Corps promptly handled orders from the High Command and served HQ, II Corps and HQ MR 5 commanding a swift spreading out to execute the assault on Da Nang. On 29 March 1975, Da Nang – the second largest city in the South – was liberated. We eliminated and scattered a large force of the enemy army, and broke through the new strategic defensive system of the enemy.
The Hue-Da Nang victory was of great significance, along with the Highlands victory, in changing for good the balance of forces between ourselves and the enemy, creating favorable conditions for us to launch the campaign to liberate Saigon.
After Da Nang was liberated, at 1630 hours 29 March, the General Staff cryptographic organization encrypted a message from Cde Le Dzuan to the theater:
The situation is changing rapidly – the revolution in the South is entering the stage of spreading by leaps and bounds. I concur with you fellows that this is the time in which we need to act promptly in an all-out effort, determined and daring. In reality, it may be considered that the campaign to liberate Saigon began at this point.... Good health and great victory to you all.
On 31 March 1975, the Central Party Politburo convened under Cde Executive Secretary Le Dzuan. In this meeting the Politburo affirmed: the revolutionary struggle in the South not only had entered the stage of spreading by leaps and bounds, but also the strategic opportunity to carry out the general offensive and uprising was ripe. Thus the Politburo resolved:
"Grasping the strategic opportunity more than before, with ideological guidance – like lightning, daring, with the element of surprise, and certain victory – be determined to carry out the general offensive and uprising in the nearest timeframe, preferably April, without delay."
A week before this historic session, the Politburo appointed Cde Le Duc Tho, member of the Central Party Politburo, to go into the South, so that, along with comrades Pham Hung and Van Tien Dzung, guidance for the offensive and uprising could be provided. Cde Nguyen Van Thinh and Cde Tran Diep were the cadre and individual from the Bureau of Encrypting-Decrypting of the General Staff selected to go serve the transfer of Cde Le Duc Tho for this task.
In order to speedily concentrate forces to win victory in the final battle, the main force corps – III Corps,[92] II Corps, and I Corps – received orders for speedy movement down to the Saigon-Gia Dinh front.
On 7 April 1975, the General Staff cryptographic organization sent Immediate message #157 from General Vo Nguyen Giap to the units: HQ, Group 559; 559th Forward; the corps; and the services and branches on the march, the entire text being as follows:
Like lightning, and even more so; recklessly, and even more so; taking advantage of every hour, every minute, rush to the front and liberate the South. Be resolved to fight and totally win.
Transmit at once to the party members and soldiers.
VAN [Vo Nguyen Giap]"[93]
In these days the army cryptographic organization from General Staff Cryptographic Directorate down to unit cryptographic organizations ensured good service to the leadership of the Politburo, the Central Military Committee, and the High Command [extended] to the theaters and regions.
At each step of the march of the wings of the army, their victories from the theaters came flooding back in messages. The atmosphere of work in the Bureau of Encrypting-Decrypting 224 in the Directorate of Cryptography of the General Staff during these days was recalled by one comrade cryptographer as follows:
The volume of work increased, fast and furious. We spread out our material to work at once. The pace of encryption and decryption increased without let-up: seven minutes, six minutes, five minutes, even four and a half minutes a message. Knocking off a minute was extremely valuable at this time.[98]
Many high-precedence messages went to the wings of the army, overseeing and urging on the axes to hurry up more, to speed the advance. In the wing to the east, when they received a message, cryptographic took it up to Cde Le Trong Tan, who joyfully embraced the comrade cryptographer, Vu Van Canh, and wrote on the message form "hoan hô co' yêú thông tin rât kip thòi" ["hurrah for the cryptographers and commo – very timely!"].
On 8 April 1975, the Politburo decided to establish the Campaign CP for the liberation of Saigon-Gia Dinh, with Cde Van Tien Dzung as commander and Cde Pham Hung as political commissar, the B2 Cryptographic Bureau being shifted over to perform the mission of campaign cryptographic bureau.
On 14 April 1975, the Politburo and the Central Military Committee approved the plan for the liberation of Saigon-Gia Dinh. The cryptographic organization sent secret message #37 from the politburo to the campaign CP. At 1900 hrs the same day, the campaign CP received it and among its contents was:
"We agree that the Saigon campaign be called the Ho Chi Minh Campaign."
In the days that followed, many secret messages of the greatest importance from the Politburo and the Main Military Committee were taken care of by the cryptographic organization, dispatching them to the theaters at top speed and with total accuracy. For the army cryptographic warriors, these were hours and minutes of the happiest flapping, honored to be handling the offensive orders of the Party – of the nation – in a period of historic importance for our race.
At 1400 hrs on 15 April 1975, at the Supreme Command Post, General Vo Nguyen Giap handed the mission to Cde Nguyen Dzuy Phe, Director of the Army Cryptographic Directorate. Cde Vo Nguyen Giap instructed: "In the recent days of special and urgent combat by our military and people on the Southern front, cryptographic cadre, soldiers, and personnel accomplished their mission in an outstanding way. The Central Military Committee commends all comrades. The combat that is under way and near at hand until total victory is urgent and decisive. The mission of ensuring the secrecy, accuracy, and timeliness of the content of orders, guidance, and commands from the Politburo, the Central Military Committee, and the High Command will be decisive vis-a-vis our determination to accomplish the liberation of the South. All comrade cadre and soldiers, Party members, group members, and personnel of the Cryptographic Directorate must be highly resolved to seek every means of ensuring this requirement."[99]
Implementing the instructions of the Comrade General, the chief of the Cryptographic Directorate encouraged the entire organization to a higher level of political responsibility, to strive upward in accomplishing the mission that had been entrusted.
In order to promptly handle important messages of the Politburo, the Central Military Committee, and the High Command going to the steering comrades in the theaters, a cryptographic team under Cde Vo Minh Chau, comprising Nguyen Xuan Phu, [Miss] Dang Thi Muon, [Miss] Vu Thi Trong, Nguyen Van Khoi, et al., was sent up to encrypt and decrypt messages right on the spot, in the work place of the Central Military Committee. In the duty team encrypting and decrypting at the work place of the Military Committee, there was very close coordination, quick reaction, and creativity with the radio team, so that messages could get out at once and the fastest encryption and decryption could be ensured. The Comrade General, through personal association and good cheer, encouraged the comrade cadre and personnel in the teams to be calm and self-confident, demonstrating speed and accuracy for the combat orders and communiques of the various theaters. In the room where they worked, cryptographic cadre and personnel encrypted and decrypted extremely important and most urgent messages carrying the signatures of comrades BA (Le Dzuan), TRUONG CHINH, TO (Pham Van Dong), VAN (Vo Nguyen Giap), THANH (Hoang Van Thai) ... and comrades SAU THO, TUAN, BAY CUONG[100]. . . messages written mainly by Cde Le Dzuan. Ordinarily General Vo Nguyen Giap personally handed messages to cryptographic: having any section of a message written by the comrade general, cryptographic encrypted that section and conveyed it at once to Communications – there were times when the comrade sat down in the room where cryptographic was at work in order to write or correct messages. Having an incoming message, once decrypted cryptographic sent it along to the leadership comrades present. With a very long message, but a requirement to communicate it most urgently, every minute, every hour counted (such as the message Cde Le Duc Tho sent back on 25 April 1975, a ten-page typewritten communique concerning the situation in theater B2: it amounted to a message of fifteen to twenty pages).
One day, around the end of April, after hearing Cde Nguyen Dzuy Phe report on the situation of the Cryptographic Directorate's service to the campaign command and control, Cde Hoang Van Thai arrived to visit and encourage the young men and women cryptographic cadre and personnel on duty serving the campaign in the work place of the Central Military Committee. Cde Hoang Van Thai praised the accomplishments of the Cryptographic Directorate's independent-activity cryptographic teams serving the quadripartite military mission and the groups of Cdes Van Tien Dzung, Le Duc Tho, and Le Trong Tan, and of the duty cryptographic team at the work place of the Central Military Committee. He issued instructions and requested that service to steerage and command in the upcoming campaign be performed such that the Politburo and the Military Committee be able to promptly grasp each stage of development of the wings of the army, and of each point of attack into the last lair of the enemy.
In these historic days of the spring of 1975, on every part of the national soil, life was motivated by the highest magnanimity. All as one people bravely advanced to achieve the final victory. The military forces blitzed into the liberation of Saigon, cryptographic cadre and personnel (616 comrades just out of school and 192 comrades in the units) rushing along as comrades in arms to the front, liberating the entire South.
The cryptographic organization of I Corps alternately engaged in operations and in the ensurance of orders transmitted by HQ and Corps headquarters, commanding the mechanized blitzkrieg troops advancing secretly along a 1,700 km stretch into the Dong Xoai sector (eastern part of Nam Bo) and taking up a consolidated position promptly in accordance with instructions from HQ.
The cryptographic organization of II Corps, after accomplishing the mission of ensuring command in the operation to liberate Hue-Da Nang, also as a unit alternated in operations and ensuring the corps command of the troops "striking the enemy and moving on, opening the road and advancing" from Da Nang down to Bien Hoa, Ba Ria, etc., on the line of advance right up to the gates on the eastern side of Saigon.
The cryptographic organization of III Corps, after serving command in the operation to liberate the Highlands and the southern provinces of Sector 5, as a matter of urgency supplemented and readjusted cadre and personnel and the types of technique to serve the corps commanding assault troops, opening the route of advancement to regroupment positions controlling the jump-off point for the assault on Saigon from the northwest, in accord with the plan of the campaign CP.
The cryptographic organization of IV Corps, after serving the corps HQ commanding the liberation of the town of Xuan Loc, continued to serve the corps command appointing units to stick close to Saigon and prepare to serve the corps assault.
The cryptographic organization of Group 232[101] swiftly developed an organizational system and a technical system, preparing to serve the command plan for the Saigon assault from the south and southwest.
The cryptographic organizations of the 5th, 3rd, and 9th divisions, and the cryptographic organizations of MR 8 and MR 9 served command and control of the mobile forces, isolating Saigon from the Mekong delta, wiping out subsector military posts of the enemy, liberating hamlets, etc., creating a springboard for attacking Saigon from the south and southwest.
The cryptographic organization of MR 5, after serving command and control in the operation to liberate Hue-Da Nang, continued to serve HQ commanding the units which, in turn, were wiping out the enemy's defensive system to the south of the military region, and to serve the mobile operational command without interruption, along a line of nearly 500 km from Quang Ngai to Nha Trang and Cam Ranh, etc., having occasions of quickly setting up liaison points – the MR Cryptographic Bureau had to swiftly transfer cryptographic key from the primary CP of the MR to the 3rd Division, some 300 km distant, to enable the 3rd Division to be in prompt touch with HQ.
While the various wings of the army were closing in on Saigon, MR 5 Cryptographic and cryptographic of the Navy units served command in liberating the Spratly Islands after an operation of three days and nights braving waves and wind.
The cryptographic liaison net system of the Navy in turn was arranged on the naval bases and ports in the South of our nation.
On 22 April 1975, the Encrypting-Decrypting Bureau of the Cryptographic Directorate of the General Staff handled a telegram from the Politburo, signed by Cde General Secretary Le Dzuan, and addressed to the campaign CP:
The military and political opportunity to open the assault on Saigon has ripened. We need to take advantage of each day – to promptly mobilize the attack on the enemy from every direction, without ceasing . . . you are all to issue instructions at once to the various directions to act promptly....
At precisely 1700 hrs on 26 April 1975, our artillery opened up on the puppet Armor School, opening the curtain for our final assault on Saigon. Cryptographic of II Corps handled the command order to wipe out some important positions, among them the Nuoc Trong base, in order to establish a springboard to facilitate the field of fire of the 130mm guns laying on Tan Son Nhat airfield.
The cryptographic organization of I Corps served the combat command of the corps in the northern and northeastern approaches.
The cryptographic organization of II Corps served the combat command of the corps in the southeastern approach.
The cryptographic organization of III Corps served the combat command of the corps in the northwestern approach.
The cryptographic organization of IV Corps served the combat command of the corps in the eastern approach.
The cryptographic organization of Group 232 served the combat command of the group on the western and southwestern approaches.
On 28 April 1975, while the cryptographic organizations of the five wings of the army were ensuring the service of combat command liberating Saigon, the cryptographic organization of the Air Force Forward CP and the cryptographic team of the hastily established station went along to serve the comrade commander of the Air Force ensuring command of the flight of A-37s (aircraft taken from the enemy) in charge of Nguyen Thanh Trung, suddenly bombing Tan Son Nhat airfield.
At 0500 on the morning of 29 April 1975 the wings of our army simultaneously opened fire and assaulted the capital.
Cryptographic cadre and personnel speedily handled messages from the Politburo and the Central Military Committee mobilizing all cadre and soldiers with great fortitude to win total victory in the historic Ho Chi Minh campaign. In that connection, the General Staff cryptographic organization ensured continuous handling of directive messages from the Politburo, the Central Military Committee, and the High Command, sent to the campaign command post.
The cryptographic organization of I Corps served the corps command eliminating enemy bases, hitting and occupying the puppet General Staff [compound].
The cryptographic organization of III Corps served the corps command hitting and occupying Tan Son Nhut airfield, afterward serving command coordination with I Corps, hitting and occupying the puppet General Staff [compound] and advancing toward Independence Square.
The cryptographic organization of Group 232 served command hitting and occupying the Capital Special Sector HQ and the Main Police HQ, the Navy HQ, and the Nha Be gasoline depot.
The cryptographic organization of II Corps served command hitting the enemy and opening the route for advancing on and occupying Independence Square.
The cryptographic organizations of IV Corps and the 3rd Division (MR 5) served corps command hitting and occupying the CPs of MR 3, the Bien Hoa Military Sector, the Thu Duc Special Forces HQ, etc.
At 1130 hrs on 30 April 1975, the liberation banner was unfurled over a housetop at Independence Square, puppet president Dzuong Van Minh having to announce unconditional surrender. The cryptographic team of a II Corps penetration unit (consisting of Cdes Than and Vong) had the honor of being present in Independence Square at this historic hour and minute and received from higher echelons the responsibility of safeguarding the official seal of the puppet Saigon authorities.
The historic Ho Chi Minh campaign was totally victorious. Cde Nguyen Dzuy Phe, Director of the Army Cryptographic Directorate, carried up to the Politburo and the Central Military Committee the telegram announcing that our forces had raised the flag over Independence Square.
In the fifty-five days and nights of the general offensive campaign and the spring uprising of 1975, army cryptographic had ensured the encrypting and decrypting for transmittal of 1,192,525 telegrams, ensuring secrecy, accuracy and timeliness to satisfy the requirements of a blitz advance and the enormously large-scale operation of our army and our people. The military cryptographic of the South alone had handled the encrypting, decrypting, and transmittal of 810,387 official messages. From the General Staff Cryptographic Directorate to the cryptographic organizations of the various levels, there had been applied a method of creating highly valuable experiences, summarized through thirty years of building and fighting, principally in the operations of Khe Sanh and Route 9-Southern Laos, the general offensive and uprising in the spring of 1968, the general strategic offensive of 1972, etc., to prepare a plan and execute the cryptographic task in order to ensure service for the command and control task in this great, historic campaign.
In order to fulfill in an outstanding manner the mission of service to campaign command and control, one of the decisive factors was the totality of the cadre and personnel of the army cryptographic branch, thoroughly permeated with the important significance of the general offensive and uprising, resolved in the strategy and clear-sighted ideological direction of the Politburo and the Central Military Committee.
[92] III Corps was formed 27 March 1975 in the Highlands, comprising the 10th, 316th. and 320A infantry divisions, 675th artillery regiment, 312th air defense. 198th sapper, 273rd tank, 545th engineer, and 29th communications regiments. Commander, Brig. Gen. Vu Lang; Sen. Col. Dang Vu Hiep, political commissar. The History of the People's Army of Viet Nam (Hanoi: Institute for Vietnamese Military History, 1990). Vol. II, Part 2, 247, 247n, 248. – Tr./Ed.
[93] Ibid., 258, identifies this historic message as #157-H-TK sent at 0930 hours, but adds that copies were sent also to the component divisions and to General Le Trong Tan. – Tr./Ed.]
[94] Resolution of the Central Military Committee Conference of June 1973.
[95] Extract from speech by Cde Le Duc Tho at the Vietnamese cryptographic branch conference recapitulating the cryptographic task in eight years of opposing America and saving the nation (21 March 1974).
[96] Namely, Cdes Cam, Uong, Bau, Sinh, Chat, Thuc, and Khoa.
[97] Five Decisive Months. Hanoi: People's Army Press, 1984, 182.
[98] Notes of Cde Nguyen Van Khoi, cadre of the Bureau of Encrypting-Decrypting.
[99] Holograph by Cde Vo Nguyen Giap, preserved in the General Staff cryptographic Directorate.
[100] Cryptonyms of comrades Le Duc Tho, Van Tien Dzung, Pham Hung.
[101] Group 232 was established in March 1975. [According to the History of the PA VN cited earlier, Group 232 was a corps-equivalent formation comprising the 5th and 3rd infantry divisions, reinforced by the 9th Division from IV Corps, plus branch troops. Commander, Maj. Gen. Le Duc Anh; political commissar, Brig. Gen. Le Van Tuong. Op. cit., 268, 271, 274. – Tr./Ed.]