British codebreaking and American secrecy in the First World War ISWS Seminar Series: Guest speaker Daniel Larsen

Beginning in late 1915, British codebreakers cracked the US diplomatic codebooks and were reading all of American diplomats' transatlantic telegraphic communications. British codebreakers easily read these communications because of a significant lack of a culture of secrecy among American diplomats before the First World War.

Driven by a conception of secrecy as being necessary only for matters of ‘national defense', a concept that did not include diplomacy, the State Department routinely published its own communications for decades before 1914. Yet this codebreaking failed to give Britain any meaningful wartime diplomatic advantage over the United States. Rather, these intelligence products primarily existed as weapons in British elites' own internal political disputes, damaging relations with the United States as a consequence