British cryptologists decode Enigma
British Intelligence decodes the first German Enigma messages. Most of Germany’s high-level military messages were encoded using a cipher machine called Enigma. Preceding the German invasion of Poland in 1939, Polish intelligence passed on to British intelligence information to break Enigma. Two Bletchley Park engineers invented Colossus, the first electronic, programmable machine in 1943. Colossus not only decoded messages, but also broke through the overlaying cipher. Now the Allies could decipher German communications before they reached the intended recipients.