Popular at the time among the lower and middle classes, Despenser's Crusade "was only widely criticised in hindsight",[1] and "for all its canonical propriety, was the Hundred Years' War thinly disguised".

Louis soon procured a French army to relieve him, and the militia of Ghent was decisively defeated at the Battle of Roosebeke on 27 November, where Philip was killed.

The fleet of Ghent escaped to England, where it kept up the war,[5] while the rebel commander Frans Ackerman sought to negotiate English support for their cause.

One side, led by John of Gaunt, put forward a crusade to establish him on the throne of Castile, and gained the support of the upper chamber, the later House of Lords.

[9] Some peers criticised the crusade as threatening Richard II's claim on France, citing the way in which Urban VI had tried to control Naples after its successful defence against the Clementist Louis of Anjou's expedition in 1381.

[10] As early as 1378, the Cardinal Pietro Pileo di Prata expressed hope that through Richard II's marriage to Anne of Bohemia, an anti-French alliance between England and the Holy Roman Empire could be forged.

[11] In 1379 Despenser published the bull Nuper cum vinea (6 November 1378) of Urban VI offering plenary indulgences to both the living and the dead in return for contributions proportional to or consistent with the donor's wealth to the general crusade against the Clementists.

)[5] In March 1381, by two bulls, Urban appointed Despenser in charge of the anti-Clementist crusade in England, and gave him the power to grant indulgences and to dispense priests to participate.

[11] A further bull, Dignum censemus, of 15 May empowered Despenser to preach the crusade in both archdioceses of England, Canterbury and York, and to take action against opponents of his message.

[11] While the crusade was preached by friars, false confessors went about extorting money, while some legitimate priests refused to hand over their collections to the war chest.

The public finances were overseen by Despenser's treasurer, Robert Foulmere, and by a London merchant, Sir John Philpot, who also acted as the expedition's banker.

King Richard II, who was advocating peace with France, ordered Despenser to await the arrival of William de Beauchamp, an experienced general, but the bishop ignored him.

"[18] According to the transcript of the bishop's later trial, the king negotiated for Arundel to gather a group of men-at-arms and archers and go to Flanders, but the "ambiguously written" letters of Despenser, and reports of speeches he had made, indicated that he would not accept a lieutenant.

[5] He later claimed that the restlessness of the 6,000–7,000 evacuees from the other surrendered towns and his lack of provisions, with the truce set to expire in a few days, forced his hand.

[19] At the time of the truce, the king: had appointed his uncle of Spain [John of Gaunt] to come quickly to [Despenser's] aid and support.

[19] Upon returning, Despenser and his captains were summoned by the chancellor, Michael de la Pole, at the insistence of parliament, which opened on 26 October.

[5] At the end of the proceedings, which took place before king and parliament, the bishop was impeached, deprived of his temporalities for two years, on the basis "of several matters, but especially of four articles".

He further claimed that he had more than quota of forces at Ypres, even though they had not all assembled at Calais; and that although Lord Neville had offered to go in the king's very presence Richard had refused permission.

His guilt was confirmed, and although he had acted "contrary to the common custom of the estate of [a] prelate of England",[20] Richard II offered to treat him as an ecclesiastic.