By far, the 445th's most notorious mission is the Kassel Mission of 27 September 1944. In cloud, the navigator of the lead bomber miscalculated and the 35 planes diverted from the rest of the 2nd Air Division and proceeded to Göttingen some from the primary. After the bomb run, the group was attacked from the rear by an estimated 150 Luftwaffe planes, resulting in the most concentrated air battle in history. The Luftwaffe unit was a "Stormgruppen", a special unit intended to attack bombers by flying in tight formations, up to ten fighters in line abreast. This tactic was intended to break the bomber formation at a single pass. The 361st Fighter Group intervened, preventing a complete destruction of the Group. Twenty-nine German fighters and 26 American planes (25 B-24 bombers and 1 P-51 Mustang) went down in a radius. Only four 445th planes made it back to the base; two made emergency landings at RAF Manston, two crashed in France, one in Belgium, another crashed near RAF Old Buckenham—representing an 88.5% total casualty rate.