The battle of the Roer (2 October 1794) was the second of two battles that forced the Austrians to abandon their last foothold in the Austrian Netherlands and retreat to the line of the Rhine. After the French victory at Fleurus on 26 June 1794 the Austrians had slowly abandoned most of the Austrian Netherlands, eventually losing touch with their Dutch and British allies. By the end of August the new Austrian commander, Franz Sebastian de Croix, Graf von Clerfayt, was holding a line on the Meuse, with his left flank running south east from Liége along the River Ourthe.
On 18 September General Jourdan attacked this Austrian position (battle of the Ourthe) and forced Clerfayt to retreat east to the Roer. The new Austrian line ran from Roermond at the right, through Jülich at the centre and down to Düren at the left, with a foothold on the west bank of the Roer at Aldenhoven (an alternative name for the battle). An isolated Austrian garrison also held out at Maastricht.
Although Jourdan was ordered to besiege Maastricht before attacking Clerfayt, he realised that the more sensible plan was to push the Austrians back to the Rhine and then mop up. He decided to concentrate his efforts against the Austrian left, although attacks would be made all along their line. General Scherer, with three divisions, was to attack on the right at Düren. He planed to use one of his divisions to outflank the Austrian line and the other two on frontal assaults. Next to him was General Hatry, who was to cross at Altorp (possibly now Altenburg). In the centre Championnet and Morlot, with two divisions, were to attack Aldenhoven and the Austrian positions to its east, and attempt to reach the river. To their left General Lefebre was to cross the Roer at Linnich, and further left Kléber, with two divisions, was to cross at Rathem and push along the river towards Roermond.
The French attack met with success all along the line. Fog delayed the start of the attack from 5 a.m. to about 10 a.m., while the attack on the French right was delayed even further by the late arrival of some of Scherer's troops.
The first French successes came in the centre, where the Austrians were forced to abandon Aldenhoven and fall back into prepared defences between the town and the river. The Austrians held onto these positions until they were threatened by Hatry to the south and Lefebre to the north. They then fell back to Jülich.
On the French left Kléber ran into determined Austrian resistance. Eventually some of the men in his two divisions, under Ney and Bernadotte, swam across the river under the cover of a heavy artillery bombardment and carried the position at Rathem. Overnight the rest of his divisions crossed the river, but they played little part in the main battle.
The most important successes came on the French right. Scherer's outflanking movement went wrong, and the division involved didn't reach the battlefield until the evening, but his remaining two divisions crossed the Roer at three in the afternoon. After a hard fight that lasted for the rest of the afternoon, the French took and held Düren.
At the end of the day the French were across the river in several places, and Clerfayt realised that his position was no longer sustainable. On the night of 2-3 October he withdrew towards the Rhine, and by 6 October the new Austrian front line ran along that river. Their last toehold in the Austrian Netherlands was gone.