Edward's crushing naval victory at the Battle of Sluys allowed him to land his army and carry out his campaign in northern France. When Edward landed he would be joined by Jacob van Artevelde, Flanders' semi-dictatorial ruler who had gained control of the County in an insurrection. By 1340 the cost of the war had already drained the English treasuries and Edward arrived in Flanders penniless. Edward had attempted to pay for his campaign through a large tax on grain and wool, however, this tax raised only £15,000 of the £100,000 predicted.

Shortly after landing Edward split his army. 10,000 to 15,000 Flemings and 1,000 English longbowmen would launch a chevauchée under the command of Robert III of Artois and the remainder of the coalition forces under Edward would go on to besiege Tournai.

Edward and his forces reached Tournai on 23 July. Apart from the inhabitants, there was also a French garrison inside. The siege dragged on and Philip was drawing closer with an army, while Edward was running out of money. At the same time, Tournai was running out of food. Edward's mother-in-law, Jeanne of Valois, then visited him in his tent on 22 September and begged for peace. She had already made the same plea in front of Philip, who was her brother. A truce (known as the Truce of Espléchin) could then be made without anyone losing face and Tournai was relieved.