The battle of Willems (10 May 1794) was an unsuccessful French attempt to continue their offensive in western Flanders, which had begun successfully with the capture of Menin and a victory over the Austrians at Mouscron (29 April).
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).
While the Allies planned for an attack on Courtrai, Pichegru decided to attack the main Allied lines in force. Three French columns were involved in the attack. At the northern end of the line General Souham attacked the Hanoverians, capturing Dottignies and Coyghem to the west of the main line, but failing at Spierres.
The second column was sent to attack around the left (southern) flank of the Allied line. It advanced from Bouvines to Cysoing, but then ran into a force of Austrians at Bachy, and its advance was stopped.
The largest column, under General Bonnaud, advanced straight along the main road from Lille to Tournai. The Allies were forced out of their advanced posts at Baisieux and Camphin, five miles west of Tournai, and the French then began to bombard the main Allied lines.
The failure of the southern French column left the right flank of this main attacking force exposed. The Duke of York gathered a strong cavalry force, made up of sixteen squadrons of British dragoons and two of Austrian hussars, and ordered them to advance towards Cysoing, around the southern flank of the main French column.
The French infantry was now exposed to repeated attacks by the Allied cavalry. At earlier engagements French attempts to form squares had been unsuccessful (including Avesnes-le-Sec, 12 September 1793 and Villers-en-Cauchies, 24 April 1794), but this time they had more success. Nine cavalry charges broke on the French squares, and the Duke of York was forced to send a brigade and four battalions of British infantry forward.
As the British infantry advanced, the French retreated in their squares north to the village of Willems, supported by a force of cavalry. The Allied cavalry, now reinforced up to twenty four squadrons, drove away the French cavalry, once again leaving the infantry exposed.
Only now did some of the British artillery reach the scene. Infantry squares were always vulnerable to cannon fire, and only now did the French squares begin to waver. The next Allied cavalry charge finally broke into one of the squares, when an officer of the Greys charged the line, knocked three men out of place on his way in and six on the way out. This square was broken, and two more soon fell. In the chaos that followed the French suffered 2,000 casualties, while the British took 450 prisoners and captured 13 guns. The British cavalry lost 30 dead and 83 wounded.
Although the French squares had eventually been broken, their prolonged resistance demonstrated that the new French army was becoming increasingly professional. The British cavalry would not break another French square until Salamanca, eighteen years later!
At the northern end of the Allied lines Clerfayt had been involved in a separate engagement, a half-hearted attack on Courtrai. By the end of the day the French were back in their original lines between Menin and Courtrai, while the Allied line now stretched from Tournai up to Courtrai. On the followed day the French attacked again (battle of Courtrai), and Clerfayt was forced to retreat north, breaking the Allied line in two. The Allies were forced to move more reinforcements west, but the main army, under the Prince of Saxe-Coburg was defeated at Tourcoing (18 May 1794). Although a second battle, at Tournai on 22 May, was drawn, the Allies were forced to continue their retreat.