The bombers that Berlin did have weren't enough to defeat Britain or the Soviet Union. Here's What You Need to Know: The Allies made ruthless use of their heavy bombers. Why didn't Germany attempt the same? An armada of German Heinkel He-111 bombers droned through the Ukrainian night sky on September 21, 1944, en route to Poltava Airfield in the Ukraine for a mission against American bombers parked at the base. The B-17 Flying Fortresses and their escort P-51 fighters were part of an experimental cooperative “shuttle” program between American and Russian forces known as Operation Frantic by which American strategic bomber crews based in England and Italy would fly against Axis targets in and around Berlin, lay over at Soviet Union airfields, and strike more targets on the return leg of their circuit.