Graduating from the U.S. Military Academy at West Point, N.Y., in 1906, Andrews was commissioned in the cavalry, serving in the Philippines and Hawaii, but in 1917 he transferred to the new air service, rising to lieutenant colonel by the end of World War I. After holding a number of routine service assignments, he was named commander of the newly created General Headquarters Air Force in 1935.

A determined though moderate advocate of strategic air power, Andrews is credited with development of the Boeing B-17 bomber; his command became the model for the powerful army air forces of World War II. During the war Andrews, as air commander in the Caribbean and later as head of the Caribbean defense command, was the first U.S. airman to command an entire theatre. He was promoted to lieutenant general in 1941. In February 1943, three months before his death in an air crash, he assumed command of all U.S. forces in Europe, succeeding Gen. Dwight D. Eisenhower when the latter was named Allied Commander of the North African theatre of operations.