decades of English-French infighting

You've described ALL English/French relations, though that can describe all the UK, reminds me of my favourite joke about Britain:

Britain is the most tolerant country in the world why,

The Scots hate the English, The Welsh hate the English, The Irish hate the English, The English hate everyone including the majority of the English

That's why they are the most tolerant people in the world, living and working with people they can't bloody stand!