Blucher ordered 3rd and 4th corps to attack the isolated 13th French corps at Geilenkirchen.
The two Prussian corps were widely separated, and 3rd corps was a long way from the Prussian headquarters. As a result it was impossible to coordinate the attack.
Rouget had orders to hold Geilenkirchen if possible, but he also had orders to retire on Heerlen if necessary. He was well aware of his isolated position, and that both Prussian corps were likely to attack him. He had warned MacDonald of the threat, and that he intended to retreat should the attack develop.
At first light his skirmish line warned him that both enemy corps were marching on Geilenkirchen. Rouget immediately ordered his corps to retreat to Heerlen. 1st infantry brigade, supported by the corps artillery, would hold Geilenkirchen to cover the retreat.
10th infantry brigade of 3rd Prussian corps bore the brunt of the attack on Geilenkirchen. They suffered 400 casualties but finally took the town.
As the Polish troops retreated from the town three guns and 100 gunners were overrun by the Prussian attack and cut down.
By nightfall the Prussians were in firm control of Geilenkirchen and 13th Polish corps in retreat towards Heerlen