The Army is the main ground force of the United States armed forces. The U.S. Army is the largest of all five branches of the military.

The U.S. Navy is the branch of the military responsible for operations at sea. The Navy also uses aircraft in its operations, and it often works together with the Marine Corps.

"Learn about the powerful soldiers who make up the U.S.Marines, including what they do and the training it takes to become one"--

The Coast Guard does its main work during peacetime. It enforces all federal laws that relate to maritime activities and works with other federal agencies to protect the United States from terrorism. Discover more in Coast Guard, one of the titles in the U.S. Military Forces series.