At this point, although the British and Dutch contingents in the allied army remained nominally under Coburg’s command, the Austrian and the Anglo-Dutch forces functioned essentially separately and with no regard for one another.

On 5 July at Waterloo, Prince Coburg and the Duke of York, commander of the British contingent, agreed to defend a line from Antwerp to Louvain, Wavre, Gembloux and Namur, but Coburg promptly cancelled this agreement the next day when attacked by Jourdan and retreated with the Austrians towards Malines (Mechelen) and Louvain (Leuven), vacating Brussels along the way.

A week later, French attacks captured Malines and Louvain, prompting Coburg to begin a retreat back across the Meuse, eventually crossing at Maastricht on 24 July, occupying a defensive line on the east bank.

The Austrians held their position on the Meuse through August, as the Army of Sambre-and-Meuse awaited the return of some 40,000 men that had been detached under Barthelemy Scherer to besiege and recapture Coalition fortified towns that had now been abandoned in the rear following the allied retreat.

The remaining 105,000 men remaining were organised in divisions as follows:[5]: 248 Left Wing (Kleber) Centre (Jourdan) Right Wing (Scherer) Clerfayt's 76,000-strong army was deployed behind the steep-banked Roer with its left flank at Düren and its right flank at Roermond.The positions around Aldenhoven were entrenched, as were other portions of the line,[6] and the Austrians had destroyed all bridges and dug up all fords along the river.

Meanwhile, Kléber and the Left Wing were instructed to move upstream from a position opposite Roermond and cross the Roer at Ratheim (near Hückelhoven).

[5]: 247 Bernadotte then swam the Roer south of Ratheim with the 71st Demi-Brigade and four companies of grenadiers, supported by artillery moved forward by Kleber.

On the left, Lefebvre’s division advanced in a line of battalion columns, captured Linnich, and drove the Austrians back to Genevich on the right bank.

[11] The divisions captured Aldenhoven and forced the Austrians to fall back to their prepared fortifications behind the town, where they held until they were threatened from the flanks by Lefebvre's and Hatry's successes.

Hacquin then joined them at 7pm from the direction of Eschweiler and the Bergheim forest, but arrived too late in the day to make any contribution to the main attack.

[4]: 138–9 By the end of the day, Scherer's corps had completely crossed the Roer and captured Düren, outflanking and essentially compromising Clerfayt's entire river defence line.

[4]: 139 Reaching the Rhine also freed Jourdan to reinforce Duhesme at Maastricht, sending Kleber’s corps to enable more aggressive siege operations.