[1] With the departure of the Tiger Moths, Bottisham was transferred to 241 Sqn Army Co-operation Command with Westland Lysanders, Curtiss Tomahawks, North American Mustang Mk 1's, moved to Ayr.

A number of other Royal Air Force squadrons used the airfield before it was turned over to the United States Army Air Forces (USAAF): With the arrival of large numbers of USAAF fighter groups in 1943, Bottisham was allocated to the Americans and assigned designation as Station 374 (IM).

The group consisted of the following squadrons: The 361st FG entered combat with Republic P-47 Thunderbolt aircraft on 21 January 1944 and converted to North American P-51 Mustang's in May 1944.

The unit served primarily as an escort organisation, covering the penetration, attack, and withdrawal of Boeing B-17 Flying Fortress/Consolidated B-24 Liberator bomber formations that the USAAF sent against targets on the Continent.

It attacked such targets as aerodromes, marshalling yards, missile sites, industrial areas, ordnance depots, oil refineries, trains, and highways.

It participated in the assault against the German Air Force and aircraft industry during Big Week, 20–25 February 1944; the Normandy invasion, June 1944 and the Saint-Lô breakthrough in July.