The battle of Courtrai (11 May 1794) was a minor French victory over the Austrian army in western Flanders that forced the main Allied army to move west in an attempt to restore the situation, and thus led directly to the French victory at Tourcoing (17-18 May).
When the French offensive began the main Allied army, by then under the command of the Emperor Francis II, was engaged in the siege of Landrecies (17-30 April), close to the centre of the long front line between the Allies and the French, which at that time ran roughly along the borders of Belgium. A smaller covering army, under the command of General Clerfayt had been left to watch western Flanders, and had very nearly been overwhelmed when the French offensive began. After his initial successes at Menin and Mouscron, General Pichegru, then commanding the French Armée du Nord, took up a position between Menin and Coutrai, on the left bank of the Lys, and then paused.
This gave the Allies time to respond to the new French threat. By 3 May the Duke of York reached Tournai. Between them Clerfayt and the Duke of York now had 40,000 men, spread out between Tourani and Spierres. The Allied position, facing west, was to the south east of the main French army – Spierres is roughly six miles to the south east of Courtrai. Pichegru had between 40,000 and 50,000 men in his main army, with another 20,000 men under General Bonnaud at Sainghin, five miles south-east of Lille (about ten miles to the west of the Allied left wing at Tournai).
On 10 May both the Allies and the French attacked. The Allied attack, at the northern end of the line, saw Clerfayt cross the Lys and capture some of the outposts around Courtrai. By the end of the day Clerfayt, and the northern (right) flank of the Allied line was based around Lendelede. To the south the French attacked the Duke of York (battle of Willems), and were repulsed.
On 11 May the French attacked again. This time General Souham attacked the centre of Clerfayt's position at Courtrai, while Generals Malbrancq and Macdonald attacked his flanks. Two French attacks were repulsed, but a third attack pushed back the Austrian left flank, which linked Clerfayt to the Duke of York's army to the south east. With this flank broken, Clerfayt realised that he would have to retreat, and pulled back towards Theilt. Estimates of casualties suffered during the fighting vary, with French losses give as 700 and Austrian as between 700 and 1,500.
In the aftermath of this French victory Saxe-Coburg and Francis II were forced to choose whether they wanted to concentrate against the French offensive on the Sambre or in Flanders. They chose to move west to join with the Duke of York to carry out an overcomplicated attack on the French positions (battle of Tourcoing, 17-18 May 1794), which ended in failure. The French then moved onto the attack, although their attack on the Allied position at Tournai (22 May 1794) ended in failure. The main focus of the campaign then moved east to the Sambre, where General Jourdan began a siege of Charleroi. The Allied effort to lift this siege ended with defeat at Fleurus on 26 June, and the entire Allied position in Belgium began to unravel.