Lens is a fortified city in Flanders, modern day Belgium. The city had been captured by the French in 1647. As France began to experience a rebellion of the nobility against the leadership of Cardinal Mazarin, known as the Fronde, the Spanish saw an opportunity to retake Lens and possibly gain ground. The Prince de Condé rushed from Catalonia to Flanders and an army was cobbled together from Champagne, Lorraine as well as Paris. The French army was 16,000 men (more than half were cavalry) and 18 guns. The Spanish army was larger, compromising 18,000 men (also more than half cavalry) and 38 guns. The armies drew up, but the Spanish were on high ground and Condé decided not to attack. As the French retired the Spanish cavalry skirmished with the French rear guard and the engagement escalated until the armies were fully engaged. The Spanish infantry pushed back the French, breaking the Gardes Françaises regiment, but the superior French cavalry were able to defeat their counterparts and envelop the center.