[paraphrase, not a quotation] In 1950 Turing proposed replacing the question "can machines think?" with a game: can a machine hold up its end of a typed conversation well enough that an interrogator can't reliably tell it from a person? He then went through objections one by one, including the argument from consciousness. (after A. M. Turing, "Computing Machinery and Intelligence", Mind, 1950)

Before that there was the war. Marian Rejewski of the Polish Cipher Bureau first broke Enigma late in 1932, working from mathematics. In 1939 Turing produced the initial design of the British bombe, building on Rejewski's bomba. More on Enigma and why it fell on the secrecy page.