On 13 August KG 55 was involved in "Adlertag" the all-out offensive against the Royal Air Force (RAF) in southern England, attacking the port of Plymouth, Feltham and RAF Middle Wallop without loss. The following day, KG 55 was to suffer its most significant loss. On 14 August 1940 He 111P G1 + AA was shot down near the Royal Naval Armament Depot at East Dean in Hampshire. "Geschwaderkommodore" "Oberst" Alois Stoeckl and his crew were killed. He was replaced by "Major" Hans Korte of I./KG 55. "Major" Friedrich Kless took over command of I./KG 55. Stoeckl and his crews were able to bomb the airfield but the "Kommodore" fell to the RAF ace John Dundas. KG 55 continue to operate against RAF airfields. On 16 August 1940 it bombed Heathrow Airport. On 26 August it took part in "Luftflotte" 3's last major daylight raid for three weeks as the air fleet was reassigned to attacking the West and East Midlands industrial areas.