During the German occupation of the Netherlands, Frans den Hollander remained Director of Artillerie Inrichtingen, but he had contact with the Dutch government in exile. The Nazi's demanded immediate reopening of the factories following the surrender of the Netherlands, but Den Hollander and his superiors, Dutch Commander-in-chief Henri Winkelman and Secretary-General Cornelis Ringeling refused this initially, and succeeded in delaying the resumption of production for about a month. On June 20, 1940 production resumed. The Nazis kept the plants working during the war, but the workforce fell sharply. The company also tried to make as many civilian products as possible. This could be because the machine factory was sold in 1941. The Delft factory was also dismantled in secret in 1941. In 1944, when the Allies began to advance through The Low Countries and through the Hunger Winter the Artillerie-Inrichtingen factories were closed.