After successfully leading the suffragist movement in Montana, Jeannette Rankin became the first woman elected to Congress. A progressive Republican and a pacifist, Rankin joined fifty‐six other members of Congress on 4 April 1917 in voting against U.S. entry into World War I. This vote contributed to her defeat when she sought election to the U.S. Senate in 1918.

Rankin continued to work for world peace. In 1919, she served as a U.S. delegate to the Second International Congress of Women in Zurich. In 1929–39, she worked as a Washington lobbyist for the National Council for the Prevention of War. She ran a blistering campaign against President Franklin D. Roosevelt's foreign policy in 1940; Montana voters returned her to Congress. Still committed to pacifism, Rankin voted unsuccessfully against the Lend‐Lease Act and Agreements, the draft, the repeal of the Neutrality Acts, and increased military expenditures. Despite the attack on Pearl Harbor in December 1941, Rankin cast the sole vote against U.S. entry into World War II, the only member of Congress to vote against U.S. entry in both world wars. She was not reelected in 1942.