S.J. Res. 116, Declaration of War on Japan, December 8, 1941
On December 8, 1941, Congress approved President Franklin D. Roosevelt’s request for a declaration of war on Japan with only one dissenter. The vote was 82–0 in the Senate and 388–1 in the House. Representative Jeannette Rankin of Montana, a dedicated pacifist and the first woman elected to Congress, cast the only vote against the declaration of war.
Records of the U.S. Senate, National Archives and Records Administration
World War II: Declaring War on Japan
At 7:55 a.m. on December 7, 1941, Japanese naval and air forces launched a surprise attack on the U.S. naval base in Pearl Harbor, Hawaii, with devastating results. In less than two hours, Japanese bombers destroyed 19 American naval ships and more than 300 airplanes. A total of 2,403 Americans lost their lives; 1,178 others were wounded. Speaking before a joint session of Congress the next day, President Franklin D. Roosevelt requested a declaration of war on Japan. Congress approved the resolution in less than an hour.
That day ended isolationism for any realist.
Senator Arthur H. Vandenberg of Michigan, The Private Papers of Senator Vandenberg, 1941