Paratroopers or Fallschirmjäger as they are known in German, were the elite parachute troops (Fallschirmtruppe) of the Luftwaffe during the Second World War. Although the Americans and Italians, and to a greater extent, the Russians had experimented with airborne troops, it was the Germans who pioneered vertical envelopment using parachute, glider-borne and air-landed troops to conduct successful airborne operations in the early stages of the war. The man considered as the innovator and father of the German airborne forces was General Kurt Student and his vision would add a new dimension to warfare inspiring both the British and Americans to develop their own airborne forces. The newly raised Fallschirmjäger formations took part in airborne and glider operations from April to May 1940 in Norway, Denmark, Belgium and Holland to attack and hold vital airfields, bridges and in one case an impregnable Belgian redoubt in support of ground operations in the west. On 20 May 1941, Fallschirmjäger formations would take part in their largest airborne assault of the war, Operation Mercury, the airborne invasion of Crete. Due to the heavy losses incurred during this operation, Hitler vetoed any further large scale airborne operations. With the exception of several small scale parachute and glider missions, Fallschirmjäger were mainly utilised as elite infantry for the remainder of the war fighting on all fronts and often used as a fire brigade to support conventional forces.