The North American Aviation P-51 Mustang played a significant role as a fighter aircraft for the United States Army Air Forces (USAAF) during World War II. By the end of the war, the USAAF claimed to have destroyed approximately 4,950 enemy aircraft in the air using Mustangs, marking it as one of the most effective fighters in the European theater.
During WWII, the Air Force was not an independent branch and was part of the Army. After WWII concluded, in 1947, the Air Force became a separate entity and inherited most of the Army's aircraft, including Mustangs. These planes continued serving into the Korean War before being replaced by jet fighters.
The P-51 Mustang was initially developed for Britain by North American Aviation after being approached to build Curtiss P-40 fighters for the Royal Air Force (RAF). Instead, North American developed its own fighter named Mustang I by Britain. The USAAF took interest and acquired its first Mustangs in 1941.