The occupation of Brussels by German forces on May 17, 1940, was a pivotal moment during World War II as it marked Belgium's transition from a neutral nation to one under Axis control. Prior to the invasion, Belgium had declared neutrality and hoped to avoid the conflict engulfing much of Europe. However, the rapid German advance through the Low Countries, beginning with the invasion of the Netherlands on May 10, demonstrated the overwhelming effectiveness of Blitzkrieg tactics, characterized by quick, coordinated strikes using combined air and ground forces. Within a week, the German military had captured significant portions of Belgium and was able to establish a foothold in Brussels. This occupation was a crucial aspect of their broader strategy to secure Western Europe and protect Germany's northern front.

Once occupied, Brussels became a center for German military operations and administration in Belgium. The German authorities quickly dismantled existing Belgian governmental structures and replaced them with a military administration, enforcing strict regulations and harsh measures against resistance. The occupation affected the daily lives of Belgian civilians, from restrictions on freedoms to forced labor. Various resistance movements began to emerge in reaction to the oppressive regime. Furthermore, the occupation disrupted social, economic, and cultural life in Brussels and the wider region. Many Belgians faced challenges in dealing with German policies, leading to increased tensions among the population and contributing to a sense of nationalism that would resurface during the liberation efforts in the years to follow.