WI: English victory at the Battle of Castillion

[phil03]

Having Lancastrian France pay for itself did work fairly well and was not unpopular in Normandy until crop failure devastated the local economy. It is hard to motivate people to pay taxes for good government and defense of the realm when they have no food to eat or money to pay.

Normandy was a special case tough, as it had a bunch of english settlers and benefited from being, in many ways, the center of the whole operation. Outside of it, Calais and Gascony it worked, kinda, ish, as long as they could credibly present it as helping finish the stuborn Dauphin more quickly and bring peace back for the common good.

After Orléans, tough, the willingness of the population and the elites started to nosedive and it only got worse as it became more and more clear that the tide had turned.

 

[Dark Void]

Maybe Henry VI could come to an agreement with Parliament in the 1440s to defend Normandy then? IIRC there was a dispute between them over whether they should reform the tax system and/or the King Household or repair and upgrade the fortifications in Normandy.

So the best possible POD is to get them to modernise their military so that they are on par with the French?

The Battle of Castillion, was a complete disaster for the English in OTL. It saw the death of John Talbot "The English Achilles", one of England's most able commanders, and the fall of English Gascony. The latter resulted in King Henry VI's breakdown, which later necessitated the appointment of Richard of York as Lord Protector, which helped lay the groundwork for the Wars of the Roses. So what if the English won at Castillion?

Prior to news of the defeat, Henry VI was described as being full of energy, with many believing that he might actually lead an army against the French in person, so might that happen here? Could the English manage to keep hold of Gascony and negotiate a peace with the French? Or would the territory fall anyways?

Simply put, Castillon was either the English repel the French or the French Win. Either way, France will kick England off of the Continent, 1454 at the latest.
England does not have the resources or money to modernize its military at the moment, as well as the starting power disputes with the Crown and Nobility, England loses either way.