It was not until 11 August 1942 that he claimed his first victory, an Royal Air Force (RAF) Vickers Wellington bomber southwest of Helgoland island.

Although Sommer himself didn't add to his tally that day, Heinz Knoke and his pilots of sister-squadron 5./JG 11 had a degree of success by air-to-air bombing - dropping bombs into the middle of the bomber formations, primed on a short time-delay fuse, to break up and scatter the formation to make individual aircraft more vulnerable.

[8] Desperate to provide any sort of fighter cover, the Allies were trying to develop jettisonable fuel-tanks on their P-47D Thunderbolts to give them extra range.

This raid marked the operational debut of the long-range P-47s, now finally able to escort the bombers well into the Reich, and despite Sommer's success, II./JG 11 took its heaviest losses to date.

Another aspect was the vast increase in numbers - his 18th victory, a B-17, was one of 650 bombers sent on Mission #182 to bomb the aircraft factories in the Brunswick area.

The bad weather of January 1944 limited operations but February saw the advent of the P-51 Mustang - a fighter capable of escorting the bombers for the full 100% mission distance, forever tipping the scales in the Allies favour in the Reich bombing campaign.

February 20 was the start of Operation Avalanche, better known as 'Big Week', a coordinated assault on the Luftwaffe, its airfields and its factories, then in March attention turned to Berlin.

[11][12] At the time of his death, Hauptmann Sommer was 24 years old and one of the Luftwaffe's highest scoring Viermot-Töters (Bomber-killers) with 14 (or 15) of his confirmed 20 victories being Viermots.