Editing Trench code (section)

==U.S. troops==
The Americans were relative newcomers to cryptography when they entered the war, but they did have their star players. One was [[Parker Hitt]], b. 1878,  who before the war had been an [[Army Signal Corps]] instructor. He was one of the first to try to bring [[United States Army|US Army]] cryptology into the 20th century, publishing an influential short work on the subject in 1915 called the ''Manual for the solution of military ciphers.''<ref>{{cite web | url=https://archive.org/details/manualforsolutio00hittrich | title=Manual for the solution of military ciphers | date=1916 | publisher=Fort Leavenworth, Kan., Press of the Army Service Schools }}</ref> He was assigned to France in an administrative role, but his advice was eagerly sought by colleagues working in operational cryptology. Another Signal Corps officer who would make his mark on cryptology was [[Joseph Mauborgne]], who in 1914, as a [[First Lieutenant|first lieutenant]], had been the first to publish a solution to the [[Playfair cipher]].

When the Americans began moving up to the front in numbers in early 1918, they adopted trench codes<ref name=friedman1942/>{{rp|p. 222}} and became very competent at their construction, with a [[Captain (land)|Captain]] [[Howard R. Barnes]] eventually learning to produce them at a rate that surprised British colleagues. The Americans adopted a series of codes named after rivers, beginning with "Potomac". They learned to print the codebooks on paper that burned easily and degraded quickly after a few weeks, when the codes would presumably be obsolete, while using a typeface that was easy to read under trench conditions.