[1] The Group was the primary command and control organization for all Army Air Corps units in the Commonwealth of the Philippines from 1919 until the eve of World War II in November 1941.

The 2d Aero Squadron, having served in the Philippines beginning in 1915, was transferred back from Rockwell Field, California in 1920 after training duties in the United States during the war.

The 3d Aero Squadron, also a stateside training unit during the war, was transferred from Mitchel Field, New York in 1920.

Another mission of the 4th Composite Group during the 1920s was aerial mapping of the Philippines, the topography of many of the islands were largely unknown.

With war clouds forming, a reinforcement effort was made to the Air Corps units in the Philippines.

On 24 October 1940, President Franklin Roosevelt signed an executive order requisitioning all the undelivered P-35s sold to Sweden and impressing them into the USAAC.

In September, the 17th was moved to the still uncompleted Nichols Field when word was received that space at Clark was needed for B-17 Flying Fortresses of the incoming 19th Bombardment Group.

[3] With the large number of units being deployed to the Philippines during the buildup of forces in the summer and fall of 1941, the 3d, 17th and 20th Squadrons were reassigned to the new 24th Pursuit Group, which was activated at Clark Field.