Official Declarations of War by Congress

The Constitution grants Congress the sole power to declare war. Congress has declared war on 11 occasions, including its first declaration of war with Great Britain in 1812. Congress approved its last formal declaration of war during World War II. Since that time it has agreed to resolutions authorizing the use of military force and continues to shape U.S. military policy through appropriations and oversight.

Declaration of War with Great Britain, 1812

On June 17, 1812, Congress approved a resolution declaring war with Great Britain. The Senate approved the resolution by a vote of 19-13.

Declaration of War with Mexico, 1846

On May 12, 1846, Congress approved a resolution declaring war with Mexico. The Senate approved the resolution by a vote of 40-2.

Declaration of War with Spain, 1898

On April 25, 1898, Congress approved a resolution declaring war with Spain.

Declaration of War with Germany, 1917

On April 6, 1917, Congress approved a resolution declaring war with Germany. The Senate approved the resolution by a vote of 82-6 on April 4, 1917.

Declaration of War with Austria-Hungary, 1917

On December 7, 1917, Congress approved a resolution declaring war with Austria-Hungary. The Senate unanimously approved the resolution, 74-0.

Declaration of War with Japan, 1941

On December 8, 1941, Congress approved a resolution declaring war with Japan. The Senate unanimously approved the resolution, 82-0.

Declaration of War with Germany, 1941

On December 11, 1941, Congress approved a resolution declaring war with Germany. The Senate unanimously approved the resolution, 88-0.

Declaration of War with Italy, 1941

On December 11, 1941, Congress approved a resolution declaring war with Italy. The Senate unanimously approved the resolution, 90-0.

Declaration of War with Bulgaria, 1942

On June 4, 1942, Congress approved a resolution declaring war with Bulgaria. The Senate unanimously approved the resolution, 73-0.

Declaration of War with Hungary, 1942

On June 4, 1942, the Senate approved a resolution declaring war with Hungary. The Senate unanimously approved the resolution, 73-0.

Declaration of War with Rumania, 1942

On June 4, 1942, the Senate approved a resolution declaring war with Rumania. The Senate unanimously approved the resolution, 73-0.