Luftwaffe bombing

The fortress was subjected to heavy Luftwaffe bombing later on the same day, to which the fortress could only reply with two Bofors 40 mm L/60 anti-aircraft (AA) guns and three Colt M/29 7.92 mm (0.312 in) AA machine guns at Seiersten Battery, as well as another four Colt M/29 7.92 mm AA machine guns at Håøya Battery, but again there were no Norwegian casualties. Initially, four machine guns on the roof of the Main Battery also returned fire, but these had to be abandoned early on.

One of the two 40 mm guns became unserviceable after only 22 rounds; the other gun kept firing until 12:00, but to little effect. After a break in the attacks from 12:00 to 13:30, during which time Lützow bombarded Hovedøya, the Luftwaffe bombers returned at 13:30 and soon strafed the remaining Norwegian anti-aircraft guns, forcing the crew to seek shelter in the nearby forest at around 14:00. In all, the fortress was subjected to nearly nine hours of air attack, during which time around five hundred bombs—ranging from 50–200 kg (110–440 lb) in size—were dropped on Oscarsborg. Amongst the bombers that attacked Oscarsborg were twenty-two long-range Junkers Ju 87R \”Stuka\” dive bombers of Sturzkampfgeschwader 1 under the command of Hauptmann Paul-Werner Hozzel, operating from Kiel-Holtenau airport in northern Germany.