From September 1936 to July 1938, Turing spent most of his time studying under Alonzo Church at Princeton University, in the second year as a Jane Eliza Procter Visiting Fellow. In addition to his purely mathematical work, he studied cryptology and also built three of four stages of an electro-mechanical binary multiplier.
The Republic proved ineffective militarily, relying on disorganised revolutionary militias. The Republican government under Giral resigned on 4 September, unable to cope with the situation, and was replaced by a mostly Socialist organisation under Francisco Largo Caballero. The new leadership began to unify central command in the republican zone.
On 21 September it was decided that Franco was to be commander-in-chief (this unified command was opposed only by Cabanellas), and, after some discussion, with no more than a lukewarm agreement from Queipo de Llano and from Mola, also head of government. Emilio Mola y Vidal, 1st Duke of Mola, Grandee of Spain was one of the three leaders of the Nationalist coup of July 1936, which started the Spanish Civil War.
On 21 September, with the head of the column at the town of Maqueda (some 80 km away from Madrid), Franco ordered a detour to free the besieged garrison at the Alcázar of Toledo, which was achieved on 27 September.
On the Nationalist side, Franco was chosen as chief military commander at a meeting of ranking generals at Salamanca on 21 September, now called by the title Generalísimo.