The German Air Force, led by Hermann Goering, contributed many units of ground forces to the war in Russia as well as the Normandy front. In 1940, the Fallschirmjaeger paratroops conquered the Belgian Fort Eben-Emael and took part in the airborne invasion of Norway, but after suffering heavy losses in the Battle of Crete, large scale airdrops were discontinued. Operating as ordinary infantry, the 1st Fallschirmjaeger Division took part in the Battle of Monte Cassino. The Luftwaffe Field Divisions were eventually considered by historians to be a drain on manpower and resources that would have been better used in Army formations, and are used as an example of how poorly co-ordinated the three branches of the Wehrmacht were. This was partly due to the rivalry between the branches in general, but mainly due to Goering's ambitions. The Luftwaffe, being in charge of Germany's Anti-aircraft warfare, also used thousands of teenage Luftwaffenhelfer to support the Flak units.