This is just a short lesson on the history of the U.S. Air Force. This is not part of the final exam for the course, and is primarily included to fill in the story following World War II.
Circa 1905, when the Wright Brothers were first trying to sell their aircraft to the U.S. government, the Aeronautical Division was part of the U.S. Signal Corps. Operations involving aircraft and experimentation for their use in the military remained a part of the Signal Corps until May of 1918 when the U.S. Army Air Service was formed during World War I. From 1926 through 1941 aerial military units were part of the U.S. Army Air Corps, and after June 1941 they were called the U.S. Army Air Forces. Thus, for most of the time frame we have explored in this class so far, the military agency most focused on aerial combat was the U.S. Army. Through 1947 the air combat units--fighters, bombers, observation planes, etc.--were part of the U.S. Army. As an aside, the Navy also had air squadrons based on aircraft carriers as well as land-based search planes, fighters, and bombers utilized by the Marines in support of Naval and Marine operations. It was not until the National Security Act of 1947, signed by President Harry Truman, that the U.S. Air Force was created as a separate, independent department. This Air Force website provides a good narrative of the service during World War II, and the push for an independent Air Force as World War II was ending.
A good overview of the long battle between the Navy and the Army over aviation, you can read the following article by historian C.V. Glines. This article is not required for the course, but may be of interest or useful for research projects.