The Westwall (also known by the Allies as the Siegfried Line) was a German defence line that was built between 1936 and 1945. The more than 600-kilometre-long line stretched from Cleves, on the Dutch border, to Switzerland.

The defence system was a chain of tank barriers (dragon's teeth), bunkers, machine-gun nests and barbed-wire fences that were intended to stop the Allied troops at the German border.

Aachen was located a few kilometres behind the new part of the line at Bocholtz. It was the first city on German territory to be targeted by the Allies. Hitler wanted to prevent that at all costs and demanded that Aachen had to be defended to the last man. German resistance was growing by the day. In the second half of September 1944, the American advance was temporarily halted at the Westwall. At Bocholtz, the frontline ran parallel to the border with Germany then. Weeks of fierce fighting ensued. Residents of the liberated Bocholtz also lost their lives in the violence of war.

Aachen was largely destroyed by bombs and artillery fire. Fierce street fighting also took place. It is estimated that the final recapture of Aachen cost more than 2,000 American lives. The losses on the German side were about the same.