Denmark's military forces were inferior in numbers and equipment, and after a short battle were forced to surrender. After fewer than two hours of struggle, the Danish Prime Minister Thorvald Stauning stopped the opposition to the German attack, for fear that the Germans would bomb Copenhagen, as they had done with Warsaw during the invasion of Poland in September 1939. Due to communication difficulties, some Danish forces continued to fight, but after a further two hours, all opposition had stopped.