The Battle of the Scheldt occurred from October to November 1944 when the Canadian 1st Army was sent to clear German forces out of the Scheldt River estuary on the Belgium-Netherlands border to open the recently-captured Belgian port of Antwerp. The Germans decided to block the river to prevent Allied reinforcements and supplies from arriving through Antwerp, and the Canadians faced heavy German resistance. The Canadian forces staged numerous amphibious assaults, obstacle crossings, and costly open ground attacks against the Wehrmacht, and they were held back by German artillery, mines, and snipers; the Germans also flooded much of the area to slow the advance. The Canadians launched an amphibious assault on Walcheren, a strategically important location that was home to massive guns that commanded the river entrance. On 1 November 1944, British commandos were sent to flush the Germans out, supported by two World War I monitors with 15-inch guns. The Germans held on for another week before they were finally overwhelmed, and Allied minesweepers cleared the seaway.
On 8 November 1944, the opening of Antwerp was completed after heavy losses, with half of the 12,873 Allied losses being Canadian soldiers. It would not be until 28 November 1944 that the harbor of Antwerp was fully demined; the first Allied supply ships would arrive that day, solving the Allied supply problem. The Allies were now able to advance towards the German frontier during their Siegfried Line campaign.