German code breaking in World War II German code breaking in World War II German code breaking in World War II achieved some notable successes cracking British Naval ciphers until well into the fourth year of the war, but also suffered from a problem typical of the German armed forces of the time: numerous branches and institutions maintained their own cryptographic departments, working on their own without collaboration or sharing results with equivalent units. This led to duplicated effort, to a fragmentation of potential, and to lower efficiency than might have been achieved. There was no central German cryptography agency comparable to the British Bletchley Park facility.
Declarations of war during World War II 1907 (or Hague II). For the diplomatic maneuvering behind these events, which led to hostilities between nations during World War II, see the article entitled Diplomatic history of World War II. Below is a table showing the outbreak of wars between nations which occurred during World War II. Indicated are the dates (during the immediate build-up to, or during the course of, World War II), from which a "de facto" state of war existed between nations. The table shows both the "Initiator Nation(s)" and the nation at which the aggression was aimed, or "Targeted Nation(s)". Events listed include those in