 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.