Final answer:
Under General Henry Arnold's direction, the US Army Air Forces expanded to 2.4 million members and over 75,000 aircraft during World War II as part of a broader military mobilization.
Step-by-step explanation:
Under the leadership of General Henry Arnold during World War II, the U.S. Army Air Forces underwent a remarkable expansion, transforming from 22,000 members and 3,900 aircraft to a staggering force of nearly 2.4 million members and over 75,000 aircraft. This monumental growth was a critical component of the overall mobilization of American military forces during the war.
The expansion extended beyond personnel to include a massive production effort, with factories churning out thousands of planes, tanks, and other essential military vehicles. General Arnold's strategic vision and organizational skills played a pivotal role in the unprecedented scale of the U.S. military's buildup, contributing significantly to the Allied victory by ensuring a formidable and well-equipped air force. The expansion under Arnold's direction exemplifies the immense industrial and human mobilization undertaken by the United States during World War II.