He accompanied the Black Prince on the Spanish campaign in 1367 and was called Felleton Guilliam qui ot cœur de lyon by Chandos Herald.
[1] When Edward III sought to detach the Flemings from their allegiance to France, Felton accompanied him to Hainault.
[1] In the winter of 1343 Felton followed the king to Brittany at the start of War of the Breton Succession, and was at the Siege of Nantes.
[1] In May following the French signed the Treaty of Brétigny, in which Felton was named one of the commissioners to receive and take formal possession of the territories ceded to the English.
Many documents addressed to him in this capacity which relate to the protracted negotiations of this period are to be found in Rymer's ‘Fœdera.’ In 1364 and 1365 he was engaged in numerous military actions in Guyenne.
[1] Felton accompanied the Black Prince in his campaign into Spain to restore Don Pedro to the throne of Castile.
Chandos Herald, who was also with this expedition, of which he has written an account in a rhymed chronicle in French, makes frequent mention of Felleton Guilliam qui ot cœur de lyon.
The heroic resistance of a handful of Englishmen and the rash bravery of Felton seem to have struck the imagination of the people of the country, where the recollection of this feat of arms is still[needs update] to be found in legend.