The Free City of Danzig, a semi-autonomous city-state established after World War I, was primarily populated by ethnic Germans. With the rise of Adolf Hitler and the Nazi Party, Danzig became a focal point of German nationalism. On September 1, 1939, Germany launched its invasion of Poland, which began the Second World War. The following day, an accelerating offensive operation was initiated in Danzig. German troops moved to occupy the city, announcing its formal annexation under German control. This act was justified by Nazi propaganda, which claimed a need to protect the German population from perceived threats from Poland.

The annexation not only illustrated Germany's aggressive expansionist policies but also set a precedent for further territorial claims in Europe. The takeover was met with minimal opposition, and the city was quickly integrated into the Reich. Symbolically, the event represented the collapse of the post-World War I order, leading to the remapping of Europe and significant shifts in national boundaries throughout the following years of conflict. The annexation also served as a grim foreshadowing of the brutal wars and occupation policies that would soon engulf much of Europe.

In addition to military implications, the event illustrated the failure of appeasement policies by European powers, who underestimated Hitler's ambitions. Following Danzig’s annexation, many other regions would fall under Nazi control, offering insights into the strategies employed by the Third Reich during their campaigns across Europe. The annexation was a pivotal moment not just for Poland but also for all of Europe, indicating a further descent into conflict that would shape the modern world.