'Humid' was the Canadian advance to the Hollandsch Diep, the wide waterway separating the area between Breda and the Dutch coast from the island of Beijerland and the waterways on which lie Rotterdam and Dordrecht, by General H. D. G. Crerar’s 1^st Army of Field Marshal Sir Bernard Montgomery’s Allied 21^st Army Group, after 'Rebound' (20 October/8 November 1944).

With Lieutenant General Sir Miles Dempsey’s British 2^nd Army on its right moving on 's-Hertogenbosch and the Maas river, and the 'Vitality' and 'Infatuate' operations on its left to clear the low-lying islands of South Beveland and Walcheren dominating the approaches to the Scheldt river estuary and the all-important port of Antwerp, the 1^st Army faced a major element of Generalfeldmarschall Walter Model’s Heeresgruppe 'B', namely General Gustav-Adolf von Zangen’s 15^th Army. In the area to the south of the Maas river, this formation had seven divisions in the form of the three within General Hans-Wolfgang Reinhard’s LXXXVIII Corps facing the 2^nd Army and the four within General Otto Sponheimer’s LXVII Corps facing the 1^st Army. An eighth German division was en route to the area, where von Zangen also had several assault gun and heavy tank destroyer units in reserve for movement to the most threatened sports of his line.

On 16 October Montgomery ordered the 1^st Army to concentrate on the task of opening the Scheldt river estuary and clearing the approaches to Antwerp, and the 2^nd Army to turn to the west to clear the area to the south of the Maas river still held by the Germans. This required a considerable reshuffling of the 21^st Army Group’s major formations, and when completed this meant that the 2^nd Army had Lieutenant General Sir Richard O’Connor’s VIII Corps holding the eastern flank of the Eindhoven-Nijmegen 'corridor', Lieutenant General B. G. Horrocks’s XXX Corps holding the Nijmegen bridgehead over the Waal river; and Lieutenant General N. M. Ritchie’s XII Corps on the western flank of the 'Nijmegen corridor' with the task of clearing the Germans from the area of 's-Hertogenbosch and Tilburg as well as the country south of the lower Maas as far west as Breda.

This left the 1^st Army to clear the area between Breda and the coast and, of course, from South Beveland and Walcheren.

No longer needed to shield the flank of the 1^st Army, Lieutenant General J. T. Crocker’s (from 10 November Lieutenant General C. Foulkes’s) I Corps of the 1^st Army shifted to the west into the coastal area and began its attack to the north on 20 October with Major General E. H. Barker’s British 49^th Division on the right and Major General H. W. Foster’s 4^th Armoured Division on the left. The 49^th Division reached Wuustwezel on the same day, and in the process took some 500 German prisoners. Advancing in the direction of Esschen, the 4^th Armoured Division encountered stronger opposition and on 21 October was sharply counterattacked from the directions of Breda and Bergen-op-Zoom. The Germans were forced back in hard fighting during which several of their assault guns were destroyed and a further 500 prisoners were captured. Esschen and the German forces round it were attacked by Supermarine Spitfire fighter-bombers of Air Vice Marshal L. O. Brown’s No. 84 Group before the area was taken by the 4^th Armoured Division on 22 October. An immediate counterattack was beaten off, and the 4^th Armoured Division veered to the west in the direction of Bergen-op-Zoom, its next objective.

On 22 October, while advancing toward Breda, the 49^th Division was hit by a strong counterattack by Generalleutnant Erwin Sander’s 245^th Division, which had been relieved in the line by the division newly arrived from the northern Netherlands. The German division had been instructed to retake Wuustwezel with the support of the LXVII Corps' artillery, but the attack was defeated with heavy losses and the division was then authorised to concentrate on blocking the approach to Breda.

Meanwhile the 2^nd Army had begun its offensive to the west from the flank of the 'corridor'. The Germans still held Tilburg and 's-Hertogenbosch as Ritchie’s XII Corps started its advance, and the 2^nd Army eventually took both towns and drove all German troops from the area to the south of the Maas river even as the I Corps cleared the coastal area.

The progress made by the XII and I Corps by the last week of the month persuaded Generalfeldmarschall Gerd von Rundstedt, the Oberbefehlshaber 'West', that the 15^th Army's front had to be reduced, and on 26 October he ordered the defence to fall back to a line linking Roosendaal and the Afwaterings Canal via Breda and Dongen. In the morning of the following day Generaloberst Alfred Jodl, chief-of-staff of the Oberkommando der Wehrmacht, telephoned von Rundstedt with Adolf Hitler’s instruction any withdrawal must be made as slowly as possible.

After taking Tilburg, the XII Corps started to advance once again, and soon found that the Germans were indeed determined to delay the Allied movement for as long as possible. Advancing from Udenhout toward Loon op Zand, Major General G. L. Verney’s British 7^th Armoured Division soon encountered strong resistance and, despite the arrival of Major General T. G. Rennie’s British 51^st Division on its right, took two days to break though the German screen of anti-tank guns and well dug-in infantry. The capture of Dongen, farther to the west, required a still longer time. After these towns had been taken, however, the British progress was more even, and by the evening of 31 October the 2^nd Army�s divisions had reached the Maas river on a 10-mile (16-km) front from a point near Keizersveer to the junction of the Afwaterings Canal with the river. To the west of 's-Hertogenbosch, however, the Germans still held the 'island' enclosed by the canal and the river.

Throughout this period, the I Corps had been fighting its way north in the coastal area. By the fall of night on 27 October Generał brygady Stanisław Maczek’s Polish 1^st Armoured Division, close to the inter-army boundary, was flanking Breda after cutting the road from Tilburg, Brigadier J. E. Bingham’s Canadian 2^nd Armoured Brigade was only a few miles from Breda, and Major General Terry de la M. Allan’s US 104^th Division, which had been lent to the 1^st Army to assist in the freeing of Antwerp, had captured Zundert. On 29 November the 1^st Armoured Division cleared Breda in house-to-house fighting, and the 4^th Armoured Division took Bergen-op-Zoom after a three-day fight. However, it was still some days before the whole of the I Corps had crossed the line between Breda and Bergen-op-Zoom via Roosendaal.

Early on 29 October von Rundstedt suggested that the 15^th Army be allowed to pull back into the area lying to the north of the Waal river, but Hitler remained adamant that this army must hold to the south of the Maas, though he did agree that elements in danger of being destroyed might be pulled back into enlarged bridgeheads. The situation continued to deteriorate during the day, and when von Rundstedt asked for new orders, during the evening Hitler reiterated his demand that the 15^th Army hold where it was, but also said that reinforcements were on their way. More importantly, it was now decided that Generaloberst Kurt Student, commanding the 1^st Fallschirmarmee, would take command of all operations in the north-west of the Netherlands from midnight the same day. This was the initial concrete movement toward the proposal made by von Rundstedt two weeks before that there should be three army groups on the West Front: Student�s Heeresgruppe �H� came into existence on 7 November in the area between Model’s Heeresgruppe �B� and the south coast of the North Sea.

Meanwhile the Allied forces had already broken through the German line between line Bergen-op-Zoom and �s-Hertogenbosch via Breda, and von Rundstedt gave his permission for a withdrawal to the line of the Mark river and the Mark Canal to ensure, if possible, that the 15^th Army was not destroyed in the area to the south of the Maas river.

On 27 October, the I Corps ordered that the 1^st Armoured Division, with the Canadian 2^nd Armoured Brigade under command, was to strike for Moerdijk and its vital bridges over the Maas river; the 104^th Division to head to the north-west for the Mark river near Standdaarbuiten; the 49^th Division to take the route to the north from Roosendaal; and the 4^th Armoured Division to punch straight forward via Steenbergen to Willemstad on the estuary at the lower end of the Hollandsch Diep. Soon after taking Breda, the Poles reached the line of the Mark river and the Mark Canal, with the 104^th Division on the river some 8 miles (13 km) farther to the west. But after severe hard-fought actions neither division had succeeded in establishing bridgeheads beyond the Mark river by the end of October as every attempt was promptly and effectively countered.

The 15^th Army was still fighting well, but had lost more than 8,000 men taken prisoner in the last 12 days, and its losses in dead and wounded had also been heavy. At the start of November, the 15^th Army nonetheless still held two bridgeheads on the southern side of the lower Maas: these were a small bridgehead just to the west of 's-Hertogenbosch facing the XII Corps, and a larger bridgehead along the line of the Mark river opposite the I Corps.

The 51^st Division of the XII Corps attacked across the Afwaterings Canal on 4 November with the support of the 7^th Armoured Division on its left flank. Benefiting from potent artillery and air support, the operation continued throughout the night, meeting little serious resistance and facilitating the chances of quick exploitation by the construction of bridges over the canal. By afternoon of 5 November the XII Corps had completed its task. The I Corps, on the other hand, had a considerably more difficult time of it, and all its divisions met very determined resistance.

To the 15^th Army's 'deliberate' withdrawal, Hitler added the order that if the Moerdijk bridges fell intact into Allied hands the specially chosen commander of its strong defending force would answer with his head. But by 5 November the remorseless pressure of the I Corps' formations, greatly assisted by the bomb and rocket attack of the aircraft of No. 84 Group, had broken the line of the Mark river, and in the next three days the I Corps closed on the Maas, although not swiftly enough to prevent the Germans from destroying the Moerdijk bridges.

The I Corps now assumed responsibility for the line of the Maas river upstream as far as Maren, to the north-east of 's-Hertogenbosch, where it relieved the XII Corps, and Lieutenant General G. G. Simonds’s Canadian II Corps was ordered to take over the Nijmegen sector from the 2^nd Army’s XXX Corps.