​​As part of their strategy to secure the ports along the Channel coast, the Canadian forces, following their victory in Boulogne-sur-Mer, advanced towards Calais. The city, under the command of Lieutenant Colonel Kurt Schroeder, had been heavily fortified on Hitler’s orders. The German High Command sought to turn major ports into "fortresses" to deny the Allies vital supply routes.

​To prepare for the assault, the Canadians launched Operation Undergo, mirroring the strategy used in Boulogne-sur-Mer. Aerial bombardments, carried out in three waves between 20 and 25 September 1944, targeted German defenses and infrastructure. On 28 September, a British bombing raid hit the nearby town of Marck, mistakenly killing around 30 French civilians, including eight members of the Bodart family.

​As the ground offensive commenced, Canadian troops encountered stiff resistance, particularly around Coquelles, west of Calais. However, the German garrison was already severely weakened. Many of its soldiers were older and demoralized, and desertions had begun even before the battle started. A 12-hour ceasefire was arranged, allowing the evacuation of 20,000 civilians still inside the city.

​Despite these difficulties, the Canadians systematically reduced the remaining pockets of resistance. By 1 October 1944, the German forces capitulated. In total, 7,500 German soldiers were captured, while others chose to flee rather than fight to the end.

​Though the capture of Calais was a crucial victory, the war left lasting scars on the city. Even months later, Calais suffered further tragedy. On 27 February 1945, a misdirected British bombing raid, aimed at Dunkirk, mistakenly struck the Saint-Pierre district of Calais, killing 97 civilians and injuring 150 others.

​The fall of Calais was a decisive moment in the Canadian campaign along the French coast. With its capture, another major German stronghold was eliminated, bringing the Allies closer to securing northern France and advancing towards Belgium.​