The British Prime Minister during most of World War II was Winston Churchill. He became Prime Minister in May 1940, succeeding Neville Chamberlain during a crucial period when Britain faced the threat of Nazi Germany. Churchill is renowned for his leadership, oratory skills, and unwavering resolve to resist Hitler's regime. He played a crucial role in rallying the British people during the hardships of the war, particularly during the Blitz, when London was bombed. His policies and strategies were instrumental in the eventual defeat of Axis powers and he remained in office until 1945, overseeing some of the most significant events of the war.