By a subsequent treaty the Flemish towns owned Edward as King of France, and declared war against Philip of Valois.

But their voice was decisive on the course of the campaign which opened in 1340.

As Philip held the Upper Scheldt by the occupation of Cambray, so he held the Lower Scheldt by that of Tournay, a fortress which broke the line of commerce between Flanders and Brabant.

It was a condition of the Flemish alliance therefore that the war should open with the capture of Tournay.

It was only at the cost of a fight however that Edward could now cross the Channel to undertake the siege.