In the morning of 14 May 1940, the German occupying forces gave the Netherlands an ultimatum: surrender, or else the city of Rotterdam would be bombed. While the Dutch army command was negotiating, heavy bombers flew towards the city. At 1.30 p.m., much of the city centre was reduced to ruins. Over eight hundred people were killed and raging fires broke out. The Germans threatened to bomb Utrecht, The Hague, Haarlem and Amsterdam next. General Winkelman, supreme commander of the Dutch army, signed the capitulation that same day.
By the authority of the Dutch government in London, the province of Zeeland remained outside the capitulation agreement. The army, augmented by two French divisions, stood its ground for a few more days. On 17 May, Middelburg was bombed, after which the province of Zeeland also capitulated.