and although inferior in the air, the Norwegians put up considerable resistance. Norwegian air strength around Oslo consisted of just 24 combat aircraft including five Tiger Moth biplanes; this force was destroyed or captured by the evening. After the first day's fighting Norwegian aerial strength fell to 54. A notable failure of the Luftwaffe during the initial invasion was caused by the Stukas of Sturzkampfgeschwader I./StG 1, who failed to silence the batteries of the Oscarsborg Fortress thus contributing to the loss of the heavy cruiser Blücher and causing the disruption of the amphibious landings in Oslo through Oslofjord. The Luftwaffe incurred considerable losses over Oslo's Fornebu airport in which Norwegian Gloster Gladiators shot down a transport aircraft in exchange for a single loss. The airport continued to be held by the Norwegians and several Ju 52s were forced to land under fire causing considerable losses to the transports. Helmut Lent, a future night fighter ace, destroyed two Gladiators and then proceeded to strafe the defenders. The Bf 110s were running out of fuel and the situation was becoming critical, until more Ju 52s approached and disgorged the airborne troops which then quickly secured the airfield. With Luftwaffe support, the Wehrmacht had established a toe-hold in Norway. The Germans had flown 680 sorties and had lost 43 aircraft destroyed or damaged. In the next few days the Luftwaffe would establish air-superiority. The British RAF Fighter Command, RAF Bomber Command and Fleet Air Arm continued to support the Allied forces, but suffered heavy losses at the hands of the Luftwaffe. The Luftwaffe had also dented the Royal Navy during the first phases of the invasion. Junkers Ju 88's of KG 30 and Heinkel He 111s of KG 26 succeeded in damaging the battleship HMS Rodney and sinking the destroyer HMS Gurkha. Focke-Wulf Fw 200 'Condors' were used to patrol the coast and report shipping positions to the Luftwaffe Kampfgruppen and U-boats in the area. Southern Norway was effectively in German hands by 20 April but the fighting in northern and central Norway lasted for some weeks. The Norwegian campaign lasted until June 1940, and with the disasters suffered by the Allies in France, British and French Forces withdrew and Norway capitulated. The campaign had cost the Luftwaffe 260 aircraft, of which 86 were transports. Personnel casualties numbered 342 killed and 448 missing. It had destroyed 96 British aircraft (43 in air-to-air