[97][98] George Dewey, who had received an appointment to lead the Asiatic Squadron with the backing of Roosevelt, later credited his victory at the Battle of Manila Bay to Roosevelt's orders.[99] After finally giving up hope of a peaceful solution, McKinley asked Congress to declare war upon Spain, beginning the Spanish–American War.[100]

War in Cuba
Main article: Rough Riders
Colonel Theodore Roosevelt
With the beginning of the Spanish–American War in late April 1898, Roosevelt resigned from his post as Assistant Secretary of the Navy. Along with Army Colonel Leonard Wood, he formed the First U.S. Volunteer Cavalry Regiment.[101] His wife and many of his friends begged Roosevelt to remain in his post in Washington, but Roosevelt was determined to see battle. When the newspapers reported the formation of the new regiment, Roosevelt and Wood were flooded with applications from all over the country.[102] Referred to by the press as the "Rough Riders", the regiment was one of many temporary units active only for the duration of the war.