Forward air control operations during World War II were begun as an ad hoc expedient to wartime conditions.
Forward air control during the war began with the Royal Australian Air Force at the Battle of Buna–Gona in November 1942, and with the British Desert Air Force in the North African Campaign the following year.
Despite prior close air support experiences beginning in World War I, the United States had no forward air control capability when World War II began. Although forward air control techniques were perfected by such US units as the 1st Air Commando Group in the China Burma India Theater, they would be ignored in the war's aftermath.
Background
Attempts to coordinate air strikes with the needs of ground forces began during World War I. Forward air control techniques were further developed during the Rif War (Morocco) and the Banana Wars (Central America and Caribbean) of the 1920s and 1930s.
When the United States Army Air Forces (USAAF) was founded on 20 June 1941, it included provisions for Air Ground Control Parties to serve with the United States Army at the division, corps, and Army headquarters. The Air Ground Control Parties functions were to regulate bombing and artillery in close conjunction with the ground troops, as well as assess bomb damage. They were thus the first of similar units to try to fulfill the functions of the forward air controller (FAC) without being airborne. However, these units were often plagued by interservice rivalry and cumbersome communications between the respective armies and air forces involved. As a result, it could take hours for an air strike requested by ground troops to actually show up.
However, the advent of World War II did not lead to a functional US air control system; the 1942 edition of the American Field Manual 31-35 did not even mention a forward air controller. Forward air control during World War II came into existence as a result of exigency, and was used in several theaters of World War II. Its reincarnation in action was a result of field expedience rather than planned operations.
Forward air control during World War II
Europe and Africa
Russian Front
While rebuilding the Wehrmacht during the 1930s, the German military valued coordination between strike aircraft and ground troops. When they launched their attack on Poland in September 1939, Stuka fighter-bomber pilots accompanying the blitzkrieg effectively directed air strikes via radio.
During Operation Barbarossa, in late 1941, Generaloberst Wolfram von Richthofen circled over retreating Russian troops in a Fieseler Storch and called in Stukas and other German ground attack aircraft on them.
North Africa
Forward air controllers were first used by the British Desert Air Force in North Africa, but not by the USAAF until operations in Salerno. During the North African Campaign in 1941 the British Army and the Royal Air Force established Forward Air Support Links (FASL), a mobile air support system using ground vehicles. Light reconnaissance aircraft would observe enemy activity and report it by radio to the FASL which was attached at brigade level. The FASL was in communication (a two-way radio link known as a "tentacle") with the Air Support Control (ASC) Headquarters attached to the corps or armoured division which could summon support through a Rear Air Support Link with the airfields. They also introduced the system of ground direction of air strikes by what was originally termed a "Mobile Fighter Controller" traveling with the forward troops. The controller rode in the "leading tank or armoured car" and directed a "cab rank" of aircraft above the battlefield.
In March 1943, a British air controller was essential at the Battle of the Mareth Line; he directed 412 strike sorties, forcing German troops to retreat from their defensive positions with heavy casualties.