The Battle of the Netherlands commenced on 10 May 1940. Kesselring's air operation was successful against the small Belgian "Aviation Militaire", which was rendered ineffective, and Royal Netherlands Air Force, though the Dutch harassed the Luftwaffe until their surrender. The paratroopers, while initially successful, ran into fierce opposition in the Battle for The Hague, and the Battle of Rotterdam. The Luftwaffe lost 54 per cent of the transport aircraft committed; 125 destroyed, 53 bogged down, and 47 severely damaged. Some 4,000 paratroops (1,200 prisoners) became casualties.