There has been a lively debate in the 1980s(?) about cannons at Agincourt.
The side refuting this did not refute it because there would not have been firearms, but because their was no mentioning of them in official quartermaster reports.
Also Crecy, some 70 years earlier (1348?) saw use of pot-de-fers.
By the 15th there were already 'bombards' in common use, though these had already been used in the 100-years-war. Big, slow-loading cannons in fixed, dug-in positions used to shell castles... well, if by shelling you mean 'throw a really big rock at them while it sounds like the heavens come crushing down'.
The War of the Roses, in the late 15th century, would not be lacking artillery for its absence on the European theatre or the English' ignorance of cannons but, if at all, for a decision by the participants, be it about honor or economics or taste.