General Arnold of WWII was a highly decorated United States Army Air Forces general and the commander of the U.S. Army Air Forces during World War II. His nickname was HAP, which is short for his full name, Henry Harley 'HAP' Arnold. He was the only five-star general in the history of the U.S. Air Force and is considered one of the most important figures in the development of air power. He was also the first military aviator to be promoted to five-star rank.