The German occupation of Luxembourg in World War II began in May 1940 after the Grand Duchy of Luxembourg was invaded by Nazi Germany. Although Luxembourg was officially neutral, it was situated at a strategic point at the end of the French Maginot Line. On 10 May 1940, the German Wehrmacht invaded Luxembourg, Belgium and the Netherlands. Luxembourg was initially placed under a military administration, but later became a civilly administrated territory and finally was annexed directly into Germany. The Germans believed Luxembourg to be a Germanic state, and attempted to suppress what they perceived as alien French language and cultural influences. Although some Luxembourgers joined the resistance or collaborated with the Germans, both constituted a minority of the population. As German nationals, from 1942, many Luxembourgers were conscripted into the German military. Nearly 3,500 Luxembourgish Jews were murdered during the Holocaust. The liberation of the country by the Allies began in September 1944, but due to the Ardennes Offensive it was not completed until early 1945.

When Luxembourg was invaded and annexed by Nazi Germany in 1940, a national consciousness started to emerge. From 1941 onwards, the first resistance groups formed in secret, operating underground and in defiance of the German occupation. Their covert activities included aiding political refugees and those evading conscription into the German forces, as well as disseminating patriotic leaflets to bolster the Luxembourgish population's spirits.