Duke John of Normandy led a French army through Hainault in revenge for their support of Edward III. The French progress was halted by the garrison of Le Quesnoy by the use of cannon. A Flemish army led by Jacques van Artevelde, with Robert de Ufford, Earl of Suffolk and William Montagu, Earl of Salisbury, was ambushed on the way to Valenciennes; the Earls of Suffolk and Salisbury were captured and taken prisoner to Paris. Philip VI joined the French army and marched to meet the Flemish army. News arrived that the French fleet had been annihilated during the naval encounter at Sluys, with the French army then retreating to Arras.