As the campaign progressed, all the belligerents, Allied as well as German, felt the effects of the lack of suitable replacements for front-line troops.

Much war materiel still had to be brought ashore across the invasion beaches and through the one remaining Mulberry harbour (the other had been destroyed in an English Channel storm).

Although small harbours, such as Isigny, Port-en-Bessin, and Courcelles, were being used, the major forward ports such as Calais, Boulogne, Dunkirk and Le Havre either remained in German hands as "fortresses" or had been systematically destroyed.

The availability of Cherbourg had been valuable until the breakout, but then the shortage of transport to carry supplies to the rapidly advancing armies became the limiting factor.

[6] In an attempt to address this acute shortage of transport, three newly arrived U.S. infantry divisions—the 26th, 95th, and 104th—were stripped of their trucks in order to haul supplies.

[11] The 6th Army Group advancing from southern France were supplied adequately from Toulon and Marseille because it had captured ports intact and the local railway system was less damaged.

This major port had been captured at 90% intact on 4 September, but the occupation of Antwerp was not enough as the 21st Army Group failed to gain sea access by clearing the Scheldt estuary.

To counteract this, about 20,000 Luftwaffe personnel were reallocated to the German Army, invalided troops were redrafted into the front line and Volkssturm units were formed using barely trained civilians.

At one point, after the Battle of the Bulge had highlighted the shortage of infantrymen, the Army relaxed its embargo on the use of black soldiers in combat formations.

The other ports were defended to varying degrees, however, and they required substantial work to bring them into use, except for Dunkirk which was sealed off to the rear of the Allied advance.

The first operation of the Rhineland campaign, Market Garden, was commanded by Montgomery and was to secure a bridgehead over the Rhine in the north, at Arnhem, which would outflank the Siegfried Line.

Market was to be the largest airborne operation in history, dropping three and a half divisions of American, British, and Polish paratroopers to capture key bridges and prevent their demolition by the Germans.

The 4th Canadian Armoured Division, moving north toward the south shore of the Scheldt around the Dutch town of Breskens, were the first Allied troops to face the formidable obstacle of the double line of the Leopold and Dérivation de la Lys Canals.

The 1st Polish Armoured Division had greater success, moving northeast to the coast, occupying Terneuzen and clearing the south bank of the Scheldt eastward to Antwerp.

Heavy casualties ensued, including the almost total destruction of the 5th Canadian Infantry Brigade's Black Watch Battalion on 13 October.

The 2nd Canadian Infantry Division began its advance toward South Beveland, but was slowed by mines, mud and strong enemy defences.

Also on 1 November, after a heavy naval bombardment by the British Royal Navy, troops of 4th Commando Brigade, (with units of 10th Inter Allied Commando, consisting mainly of Belgian and Norwegian troops), supported by specialised armoured vehicles of the British 79th Armoured Division were landed on both sides of the gap in the sea dyke.

Bergen Op Zoom was taken by the Canadians and the Polish 1st Armoured Division led by General Maczek liberated the city of Breda.

Meanwhile, the 4th Canadian Armoured Division had pushed eastwards past Bergen-op-Zoom to Sint Philipsland where it sank several German vessels in Zijpe harbour.

The US First Army advanced rapidly through northern France and Belgium during late August and early September, with its main goal being to reach the Rhine before the Germans could establish defensive positions there.

The fighting was, by all accounts, brutal street-to-street, house-to-house style urban combat and tied up the available resources of the advancing Allied armies.

This situation was caused by the rapid Allied advance through France, and compounded by the shift of logistical priority to the northern forces to secure Antwerp.

By 1 September 1944, with the last of its fuel, the Third Army managed one final push to capture key bridges over the Meuse River at Verdun and Commercy.

Five days after that, however, the critical supply situation effectively caused the Third Army to grind to a halt, allowing previously routed German forces to regroup and the reinforcement of their strongholds in the area.

Modern historians argue that the outcome was not worth the foreseeable losses, and in any case, the American tactics played into German hands.

The exhaustive fighting during Queen caused the Allied troops to suffer heavy casualties, and eventually the Germans launched their own counteroffensive—Operation Wacht am Rhein—on 16 December, which would lead to the Battle of the Bulge.

The plan called Wacht am Rhein ("Watch on the Rhine") was to attack through the Ardennes and swing north to Antwerp, splitting the American and British armies.

Because Allied lines had become severely stretched in response to the crisis in the Ardennes, holding and throwing back the Nordwind offensive was a costly affair that lasted almost four weeks.

During the two weeks that the little river was flooded, Hitler did not allow Rundstedt to withdraw German forces behind the Rhine, arguing that it would only delay the inevitable fight.

By the time the water had subsided and the U.S. Ninth Army was able to cross the Roer on 23 February, other Allied forces were also close to the Rhine's west bank.