In 1655 Turenne captured the fortresses of Landrecies, Condé and St Ghislain. In 1656 the prince of Condé avenged the defeat of Arras by storming Turenne's circumvallation around Valenciennes (16 July), but Turenne drew off his forces in good order. The campaign of 1657 was uneventful, and is only to be remembered because a body of 6,000 English infantry, sent by Cromwell in pursuance of his treaty of alliance with Mazarin, took part in it. The presence of the English contingent and its very definite purpose of making Dunkirk a new Calais, to be held by England forever, gave the next campaign a character of certainty and decision which was entirely wanting in the rest of the war.