​​​Once handed to the USAAF, the airfield was designated Station 139. The 100th Bombardment Group consisted of four operational squadrons:

​349th Bombardment Squadron

​350th Bombardment Squadron

​351st Bombardment Squadron

​418th Bombardment Squadron

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They were assigned to the 13th Combat Bombardment Wing of the USAAF.

The 100th Bombardment Group conducted its first mission on 25 June 1943. The mission targeted U-Boat facilities around the area of Bremen, Germany, and saw a loss of three aircraft and 30 crew. As the months went by and the group gained experience, their losses began to add up and they soon became known as the ‘Bloody Hundredth’ due to the losses of aircraft and crew.

Notable operations that the 100th took part in were: Regensburg on 17 August 1943 with nine aircraft lost and 90 crew, Munster on 10 October 1943 with 12 aircraft lost and 121 crew, Berlin on 6 March 1944 with 15 aircraft lost and 150 crew, and Berlin again on 24 May 1944 with nine aircraft lost and 90 crew, Merseberf on 29 July 1944 with eight aircraft lost and 72 crew, Ruhland on 11 September 1944 with 12 aircraft lost and 100 crew, and Hamburg on 31 December 1944 with 12 aircraft lost and 111 crew.

​In between these operations many others were conducted with little to no losses, but the crew were mindful of what could happen on every operation. Between 25 June 1943 to 20 April 1945, flying out of Station 139, they conducted 8,630 missions with the staggering loss of 732 airmen killed or missing and 177 aircraft lost.

​100th Bomb Group Major, John Bennett, stated that, “what the 100th lacks in luck, it makes up in courage. The men of the century have fighting hearts.”

The B-17 aircraft of the 100th Bombardment Group were marked with the distinctive black and white ‘Square-D’. This can be seen on the tail and wings of most aircraft. Following the Regensbury operation on 17 August 1943, the 100th Bomb Group received its first Distinguished Unit Citation. It then received its second following ‘Big Week’ from 20 to 25 February 1944 and the series of operations against Berlin in March 1944.