The German advance into Belgium in the spring of 1940 was swift and decisive. Belgium was militarily unprepared for war – as late as November 7, 1939, the Belgian government had called for an end to hostilities – and even if its military had been prepared, it was massively outgunned by the Nazi war machine. The invasion of Belgium, Holland and Luxembourg began on May 10, 1940.
By May 17, the Belgian capital of Brussels had fallen to the German advance, and deciding that the Allied cause was lost, King Leopold III surrendered to the Germans against the advice of his government on May 28, 1940. He would spend the rest of the war as a prisoner of the Nazis, while the majority of his government went into exile (primarily in Britain) and continued to lead Free Belgian Forces in the fight. Belgium was eventually liberated in 1944, although it was not until the end of the German Ardennes Offensive in 1945 that fighting on Belgian soil concluded.