>August
The King Charles VI and Burgundy were raising a large relief army at Arras, which was fast growing in seize.
After 9 weeks of terrible assaults Ypres was reduced to ruins but still held out.
The English decided on one last all-out attack, but when even that one was repelled they gave up the siege.
The Ghent army, who had fielded most of the manpower but did not suffer that many casualties, was dissappointed, because they thought that with just a couple of days longer the city might have fallen.
But alone they didnt dare to continue the siege, especially with the French in their back.
At least when returning back to Ghent they surprised the garrison of vital Oudenaarde and took the town by surprise,
>September
The french royal army had grown to 20k and included all major nobles, among them for the first time the montfortist Duke of Brittany.
The large host moved north, while the English fell back to the coastal towns.
John IV of Montfort arranged with his old comrades a truce and then negotiated a treaty by which the English would leave Flanders and could be evacuated; the French moved in later and sacked these towns.
It was probably the best deal for both sides, because the English prevented a total debacle, while the french campaign achieved their goals without blood and could end the insanely expensive campaign without larger sieges.
Still, it was resented by both sides, the french army wanted to kill some Anglos and felt that the Duke of Brittany had betrayed them, while the English gave away all captured positions without a fight.
There were also murmurs, that the campaign should have been used to follow the retreating english army and advance against Calais, but that was probably completely unrealistic.
While the French felt bitter against Brittany, the English against the leaders of the crusade where Bishop Despenser was impeached.