Archduke Leopold Wilhelm was appointed governor of the Spanish Netherlands in 1647 to strengthen Spain's Habsburg alliance with Austria, and began a major counteroffensive the same year.

The French cavalry on the wings, freed from any opposition, encircled and charged the Spanish center, who promptly capitulated.

The Spanish lost half their army, some 8,000–9,000 men of which 3,000 were killed or wounded and 5,000–6,000 captured, 38 guns, 100 flags along with their pontoons and baggage.

The Prince de Condé rushed from Catalonia to Flanders, and an army was cobbled together from Champagne, Lorraine, and Paris.

On 20 August the opposing armies drew up west of Lens; the Spanish held a strong defensive position on the high ground.

The center was the strongest part of the battle array, with 16 infantry battalions and 15 cavalry squadrons under the governor of Luxembourg, Major General Jean de Beck.

There was no food, fodder or water in the place, so he decided to retreat to the village of Neus some two hours march away.

There he could obtain supplies from Béthune, where he had left his baggage train, and be in position to intercept the Spanish army's movements.

[8][4][9] At 5 a.m. six guns from Cossé's artillery park fired a volley on the Spanish and the French began to retreat while still in battle formation, with the right-wing making up the rearguard.

[10][9] General Beck's Lorrainers suddenly attacked the isolated, 10-squadron-strong French rearguard under Villequier and Noirmoutier and routed them.

[9] The Archduke then gave permission to start the battle, armed himself, confessed to his Jesuit priest and fled the field, leaving his army to its fate.

[4] Condé frequently called a halt to the advance to keep the lines in order and maintain spacing to prevent the formations from bunching up.

[6] The following ranks of the French cavalry nevertheless charged through the Walloons' formation, throwing it into disorder and rapidly causing a rout.

Once the prisoners were secure, Condé's army joined Josias von Rantzau's force in the siege of Furnes.

[11][5] 3,000 of the Archduke's men lay dead or wounded and 5,000–6,000 were captured, along with all 38 guns, 100 flags, the pontoon bridges and the baggage train.

[3][12] Beck was captured and Condé lent him a carriage to take him to Arras, where he died of his wounds ten days later.

[13] First, it caused a hardening of the Monarchy's attitude toward the parlements, leading to an initial confrontation in Paris and a protracted struggle that followed.

In the end, the French victory was made irrelevant by subsequent events elsewhere, during the failure to secure Anne of Austria's regency of France while Louis XIV was too young to rule.

A civil war in France, Fronde, broke out shortly afterwards, giving Spain the chance of recovery.

[14] The Te Deum at Notre-Dame de Paris in honour of the battle ended in a riot, which caused a serious confrontation that led to the revolt.