The Wehrmacht entered the war with a minority of its formations motorized; infantry remained approximately 90% foot-borne throughout the war, and artillery primarily horse-drawn. The motorized formations received much attention in the world press in the opening years of the war, and were cited as the reason for the success of the German invasions of Poland (September 1939), Norway (April 1940), Denmark, Belgium, France and Netherlands (May 1940), Yugoslavia (April 1941) and the early campaigns in the Soviet Union (June 1941).