In 1934, Winkelman retired, but with a German invasion impending and on the mobilization of Dutch forces, he was recalled into active service in 1939 and appointed commander of Dutch air defenses. On 6 February 1940, Winkelman was also made commander of the army and navy. On 10 May, German forces invaded the Netherlands. Almost immediately, it was clear that Dutch forces could not long resist, and with the departure of Queen Wilhelmina and her ministers to Britain, Winkelman became the highest authority on Dutch territory. The government empowered him to capitulate at what he judged to be the proper time. On 15 May, Winkelman signed the instruments of surrender at Rijsoord. He then oversaw the demobilization of the Dutch army. In July 1940, he was deported to Germany as a prisoner of war, where he remained until the end of the war. On 12 May 1945, he returned to the Netherlands, and he formally retired from the army in October. In 1946, he served as a military councilor in the Special Court of Annulment. Winkelman died in Soesterberg, the Netherlands, on 27 December 1952.
Kathleen G. Hitt
Jong, L. H. de. Het Koninkrijk der Nederlanden in de Tweede Wereldoorlog (The Netherlands in the Second World War). Leiden, the Netherlands: Martinus Nijhoff, 1988.; Maas, Walter B. The Netherlands at War. New York: Abelard-Schuman, 1970.