This is an examination of codes and ciphers as they figured in American history prior to the twentieth century, prior to the era of wireless or radio communication and the advent of the electronic age. It forms a backdrop for understanding modern cryptology and the role of cryptology (notwithstanding its traditional secrecy) in the growth of this nation. Our guide is Dr. Ralph E. Weber of Marquette University, whose 1979 United States Diplomatic Codes and Ciphers, 1775–1938 (Chicago: Precedent Publishing Inc.) established him in the forefront of students of this arcane subject.

Cryptology, the art and science of code-making (cryptography) and code-breaking (cryptanalysis), depends on the prevailing state of technology and the perception of threat:

The perception of threat rises naturally in war, but it also pertains in international relations, in business competition, in politics, and even in personal matters, including financial transactions. Applying technology to protect communications (to "mask" them, to use Thomas Jefferson's term) or to exploit those of another party introduces other variables, not the least of which is cost. Cost can involve dollars of time, including personal inconvenience. Sometimes the risk is discounted, if the cost seems too great; conversely, faced with the consequences of compromised information, what seemed earlier too great a cost may well be dismissed in favor of security.

America was born out of revolutionary conspiracy. One of the principal concerns for conspirators is communication, keeping in touch, and doing so in confidence. As rebels and conspirators, the young nation's leaders had turned to codes and ciphers in an effort to preserve the confidentiality of their communications. The technology of the time was that of messenger or hand-written correspondence, hand delivered, or by prearranged signals, such as Revere's fabled lanterns, "one if by land, two if by sea." The risk was that a dispatch might fall into enemy hands through capture of a courier, and this did happen. Intercepted cryptograms yielded to cryptanalysis of an elementary sort, producing communication intelligence, COMINT. But there was no COMINT effort as we would understand the term today. The technology of the time would not have supported such a concept. (How many enemy couriers could be scheduled for systematic and regular capture, to justify thought of a sustained effort?) Nor was cryptography an organized bureaucracy; rather, it depended upon the interest, knowledge, and imagination of a few men. America was lucky to have such men when it needed them. Some were "civilians in uniform," volunteer soldiers; most were learned men, clergy (familiar with Greek, Latin, Hebrew), mathematicians, scholars – some were statesmen. Their involvement in cryptology was generally brief, but it constituted the seeds of American cryptology.

With the successful end of the Revolutionary War, the occasion for COMINT disappeared, as did the perceived need for secrecy, in the absence of an adversary. When the need subsequently arose, particularly in the case of foreign affairs – when knowledge of the plans and actions, strengths and weaknesses, of one party by another could well thwart the young republic – it was natural to return to forms of cryptography recalled from the Revolutionary experience: the dictionary code, nomenclators, simple cipher.

No formal documentation of official American government cryptography is known to have been recorded – indeed, governments and regimes have traditionally been reluctant to publicize such activities. There is little evidence that American leaders were acquainted with what we now view as the classics on the subject of cryptography, although exceptions cannot be dismissed. Historically, what was learned through cryptanalysis of another's communications has had an effect on one's own cryptography. One might speculate that what was learned through experience by government clerks or officials was passed on through "on-the-job training" and occasional notes of instruction, and some of the latter do exist. Around the turn of the eighteenth/nineteenth century, an impressive treatise of some 35,000 words was generated by an English surgeon for an encyclopedia. Written around 1807, it was another decade before Dr. William Blair's article "Cipher" appeared in a volume of the serially-issued Cyclopedia, edited by Abraham Rees in London, and an American edition subsequently appeared. In his The Codebreakers (1967), David Kahn rightly characterized the Blair piece as "the finest treatise in English on cryptology," until army lieutenant Parker Hitt's little military manual appeared in 1916. Blair distilled the essence of the art and science of cryptology from the ancients (along with an impressive bibliography for the time) and offered the results of his own study and deductions. Surely the encyclopedia piece must have been read by some in government service, yet no firm evidence of the fact, or of its influence, has been found, apart from its having been used as a training manual by the army's signal corps (or Signal Service) in the post-Civil War years. (See chapter 14.) Perhaps it would be expecting too much to find it cited (although it is known to have been a source for Edgar Allan Poe, who, in turn, is cited by others).

Dr. Weber's examples also show the influence of communication technology – the postal card, the telegraph, and the transatlantic cable – on American cryptography. Cost becomes a more dominant consideration for the government than security when electrical communications are introduced (perhaps with the exception of the Civil War years, when the War Department set up its own U.S. Military Telegraph). Manual or mechanical devices began to appear in connection with cryptography – Jefferson's well-known "wheel" or cylinder cipher is an example. By the end of the period, mechanical devices have become more sophisticated, and the age of electromechanical devices and machines is just ahead.

David W. Gaddy