The notable British prime minister known for his leadership during World War II is Winston Churchill. Serving from 1940 to 1945, Churchill is credited with inspiring British resilience against Nazi Germany through his powerful speeches and determination. His leadership during critical wartime events, including the Battle of Britain and the establishment of alliances with the United States and Soviet Union, solidified his reputation as a key figure in modern history. Churchill's legacy endures as a symbol of courage and resolve.