In Operation Rügen, waves of planes bombed and strafed targets in Guernica leaving 1,685 people dead and over 900 injured. The offensive on Bilbao was supported by ground units and extensive air operations. It proved the worth of the Legion to the Nationalist cause. The Legion also took part in the Battle of Brunete and both land and air forces were involved in the Battle of Teruel. Up to 100 sorties a day were launched during the Nationalists' counter-offensive. The continued Nationalist offensive on Aragon in April–June 1937, including the Battle of Belchite, involved bombing raids and the use of the Legion's ground forces.