The Battle of Saint-Denis was fought on August 14–15, 1678 between a French army commanded by the Marshal Luxembourg and a Dutch army under William III near Saint-Denis, a village outside Mons, then part of the Spanish Netherlands (now Belgium). It was the last battle of the Franco-Dutch War (1672–1678), fought after the peace was signed between France and the Netherlands in the Treaty of Nijmegen on August 10. The battle was one of the most fiercely contested of the whole war. Each side had about 2,000 soldiers killed.