IX Fighter Command moved to England in November 1943 as part of Normandy invasion planning.

During the winter of 1943/44 IX Fighter Command expanded at an extraordinary rate so that by the end of May 1944, its complement ran to 45 flying groups operating some 5,000 aircraft.

Initial missions from England consisted of fighter sweeps over troop concentrations and attacks on enemy positions and airfields, primarily on German 15th Army units in the Pas-de-Calais region of France as well as around Normandy and Cotentin Peninsula.

Air cover during the morning amphibious assault by Allied forces on the beaches of France was flown by Lockheed P-38 Lightnings.

With the beaches secure, groups began deploying to France on 16 June 1944, ten days after the Normandy invasion by moving P-47 Thunderbolts to a beach-head landing strip.