 There were also anti-aircraft artillery ("Marine Flak") batteries in Kristiansand, Bergen, Trondheim, Bogen, and Harstad; these were armed with 88-mm pieces.The tanks available for the German defense were "Panzer III"s (50 mm L60 and 75 mm L24) and "Sturmgeschütz III"s (75 mm L48).Fjell fortress with its triple barrel 28 cm SK C/34 naval gun turret, taken from the battleship "Gneisenau", was seen as one of the strongest fortresses in Northern Europe.