'Aintree' (i) was the Allied undertaking to take Overloon and Venraij in the German-occupied Netherlands (30 September/18 October 1944).

In September 1944 the Allies had launched the closely related 'Market' and 'Garden' operations from the Dutch/Belgian border area across the south of the Netherlands through Eindhoven and Nijmegen toward the major bridge across the Rhine river at Arnhem, with the goal of crossing the Rhine and outflanking the northern end of Germany’s 'Siegfried Linie' defences in preparation for the final drive toward Berlin. However, the Allied airborne forces were defeated at the Rhine bridge in Arnhem and the advance stopped south of the Nederrijn river, resulting in a narrow salient that ran from northern Belgium across the south-east of the Netherlands. The Germans attacked this salient from a bridgehead west of the bend in the Maas river near the city of Venlo.

The bridgehead had been established by retreating German forces, which were reinforced by troops who crossed the Maas from Germany across the bridge at Venlo. The western edge of this bridgehead ran through the Peel marshes, a fen area with marshy ground and several canals blocking an Allied advance. To strengthen the narrow corridor it held, Lieutenant General Sir Miles Dempsey’s British 2^nd Army of Field Marshal Sir Bernard Montgomery’s Allied 21^st Army Group needed to eliminate the German bridgehead near Venlo on the Maas river farther to the south, but to launch the intended attack on this bridgehead from the north it had first to capture the towns of Overloon and Venraij on the route to Venlo.

These two objectives were held by parts of Generaloberst Kurt Student’s 1^st Fallschirmarmee, which was still forming within Generalfeldmarschall Walter Model’s Heeresgruppe 'B', and here the Allies were able to pit two divisions against just one German division. The objective of the resulting 'Aintree' (i) was to secure the narrow salient the Allies had established between Eindhoven and Nijmegen during 'Market' and 'Garden', and to destroy the German bridgehead west of the Maas, in preparation for the eventual Allied advance into the nearby Rhineland area of Germany.

The key area in the path of the Allied advance was held by a mixed force whose most potent element was Oberst Erich Walther’s Kampfgruppe 'Walther', which had been of singular importance in the German defence against the 'Market' and 'Garden' undertakings and was centred on Major Berndt-Joachim Freiherr von Maltzahn’s 107^th Panzerbrigade. It was on 25 September that the brigade was ordered to move to the north-east toward Overloon, and during this movement von Maltzahn received revised orders to move to Oploo, where it was to prepare itself to engage the forthcoming Allied attack in a defensive line extending from Venraij to the Maas river near Boxmeer via Overloon and Oploo. Apart from the 107^th Panzerbrigade, this line was defended by three Fallschirmjäger battalions, one Heeresersatz battalion and one Waffen-SS battalion. During the last month of fighting, the 107^th Panzerbrigade had suffered 323 casualties, and on 30 September had a strength of 1,975 men (including 187 walking wounded), seven PzKpfw IV battle tanks (both Flakpanzer anti-aircraft and PzKpfw IV/70 gun variants), 19 PzKpfw V Panther battle tanks and 133 SdKfz 251 armoured half-track vehicles in several variants.

The result of the Allied plans and German movements was the battle of Overloon as the Allies advanced from nearby positions south toward the village of Overloon. After a failed attack on Overloon by Major General Lindsay McD. Silvester’s US 7^th Armored Division of Lieutenant General William H. Simpson’s US 9^th Army, Major General L. G. Whistler’s British 3^rd Division assumed the main burden of the task. Suffering heavy losses, the Allies captured Overloon and moved toward Venraij. The advance on Venraij resulted in heavy losses, especially around the Loobeek creek, which had been swollen by heavy autumn rains and was also mined by the Germans. During the battle, the village of Overloon was completely destroyed.

In and around Overloon some 2,500 soldiers died, making it one of the bloodier battles fought in the Netherlands during World War II. It was also the only major tank battle ever fought on Dutch soil, and large numbers of tanks, most of them British, were destroyed. The Allied losses were 1,878 men, 40 armoured fighting vehicles and three aircraft, while the Germans lost about 600 men and an unknown number of armoured fighting vehicles.

Despite the fact that both Overloon and eventually Venraij were taken by the Allies in 'Constellation' (ii), the planned advance toward the bend of the Maas near Venlo was initially postponed, partially as a result of the number of casualties the Allies had sustained, and partially as a result of the fact that the troops were needed to secure more essential targets, namely the estuary of the Scheldt river, leading to the vital port of Antwerp, and western North Brabant, between Antwerp and the salient that had been established. The offensive was eventually resumed, and by a time early in December 1944 the German bridgehead west of the Maas was destroyed.