The Battle of the Scheldt in World War II was a series of military operations led by the First Canadian Army, with Polish and British units attached, to open up the shipping route to Antwerp so that its port could be used to supply the Allies in north-west Europe. Under acting command of the First Canadian's Lieutenant-General Guy Simonds, the battle took place in northern Belgium and southwestern Netherlands from 2 October to 8 November 1944. The Canadians had been delayed, and pressure on the Scheldt left wanting, by Allied decisions to focus on Arnhem (Operation Market Garden), Boulogne (Operation Wellhit), Calais (Operation Undergo) and Dunkirk. By the time the Canadians were sent into the Battle of the Scheldt, the Wehrmacht defenders had been reinforced. The Germans staged an effective delaying action during which they flooded land areas in the Scheldt estuary and slowed the Allied advance. After five weeks of difficult fighting, the Canadian First Army, at a cost of 12,873 Allied casualties (half of them Canadian), was successful in clearing the Scheldt after numerous amphibious assaults, obstacle crossings and costly assaults over open ground. Once the German defenders were no longer a threat, it took another three weeks to de-mine the harbours; the first convoy carrying Allied supplies could not unload in Antwerp until 29 November 1944. Once Antwerp was opened, it allowed 2.5 million tons of supplies to arrive at that port between November 1944 and April 1945, which were critical to the successful Allied advance into Germany in 1945. Following the Allied breakout after success in the battle of Normandy, they began a series of rapid advances into the Low Countries, far from their initial avenues of supply along the northern coast of France. By the fall of 1944, captured ports like Cherbourg were far away from the front line, stretching Allied supply lines and causing great logistical problems. Antwerp is a deep-water inland port close to Germany. It is connected to the North Sea via the river Scheldt, which allows the passage of ocean-going ships.