Soon after he graduated from Harvard, Weinberger joined the United States Army. When Japan attacked the US Navy at Pearl Harbor in December of that year, Weinberger went to war in the Pacific Theatre of World War II. By the end of the war he served in intelligence, and became interested in politics. He came to admire Winston Churchill, who was a personal hero of Weinberger. After he left the army he went back to his hometown of San Francisco where he worked as a law clerk and a lawyer.