World War II
United States declaration of war on JapanUnited States
On December 8, 1941, the United States Congress declared war on the Empire of Japan in response to that country's surprise attack on Pearl Harbor and declaration of war the prior day. It was formulated an hour after the Infamy Speech of President Franklin D. Roosevelt. Following the U.S. declaration, Japan's allies, Germany and Italy, declared war on the United States, bringing the United States fully into World War II.