Hess was concerned that Germany would face a war on two fronts as plans progressed for Operation Barbarossa, the invasion of the Soviet Union scheduled to take place later that year. He flew solo to Britain on 10 May 1941 to seek peace negotiations with the British government. He was arrested on arrival and spent the rest of the war as a British prisoner.
The worst raid took place in the night of 10–11 May 1941, when the Palace took at least twelve hits and three people (two policemen and the Resident Superintendent of the House of Lords, Edward Elliott) were killed.
While he was at Cambridge, the Pilot ACE was being built in his absence. It executed its first program on 10 May 1950, and a number of later computers around the world owe much to it, including the English Electric DEUCE and the American Bendix G-15. The full version of Turing's ACE was not built until after his death.