The United States.

"During World War I, the United States Army formed its divisions as square divisions, in contrast to the prevailing European norm"

People volunteered

Eisenhower served in the United States Army during World War II from 1915-1953 and 1961-1969 became the rank of General of the Army.

Douglas MacArthur was an American military leader who served as General of the Army for the United States, as well as a Field Marshal to the Philippine Army. He was Chief of Staff of the United States Army during the 1930s, and he played a prominent role in the Pacific theater during World War II.

Mark R. Henry has written:

'The U.S. Army in World War II' -- subject(s): History, United States, United States. Army, World War, 1939-1945