Major (later Colonel) Delbert L. Bristol served as an Army Liaison Pilot in the early test that established organic air observation in 1942. After serving briefly on the faculty of the Department of Air Training, Lieutenant Bristol left the continental U.S. with the first group of pilots and aircraft mechanics deployed overseas in October, 1942.

After his arrival in England, and during late 1942 while in North Africa, he was the driving force in the organization of a combat zone school that trained additional pilots and aircraft mechanics to meet the Artillery's combat aviation needs until replacements from Fort Sill became available in sufficient numbers.

While serving as the Artillery Air Officer for II Corps during the Tunisian and Sicilian campaigns, Major Bristol directed and coordinated the employment of the Air Observation Posts [Pilot and Field Artillery Observer teams in radio-equipped Piper L-4 Cubs] that later was acclaimed as one of the great innovations of World War II. Calling on his experience as First Army Artillery Air Officer in Northern Europe in 1944-45, he contributed in great measure to the success of the Air OP's in combat.

In 1948-1949, while a Major on the Army General Staff in Washington, D.C., his negotiations in the Army Staff and with the Air Force, sometimes against heavy odds, assured the foundation of the Army's organic aviation following the unification of the services.