The French and Indian War (the seven years war) between the English and the French was fought 'in the backyards' of the British colonials, resulting in colonial resentment towards the French as well as their sovereign nation. Great Britain won the war, however at great cost. King George's 'piggy bank' was bankrupted and so he looked towards his colonies for its replenishment. The status-quo mercantilistic policies and the salutory neglect between the crown and her colonies for so many years were suddenly thrown into a lion's den. The crisis between the crown and the colonies was steeped in the rights of Englishmen, going back to Magna Carta 1215. Although many of the colonists had already developed an 'American' reality they were true to their enlightened beliefs. The Seven Years War pitted the reality of a bankrupted monarchy against the ideology of its foreign subjects.
Main reasons why the French and Indian War/ 7 Years War causes the crisis between the colonies and Britain:
1. This is the biggest one: it causes the British government to go too deep in debt. So they want money to make up for that. That's why they start trying to tax the colonies and trying to crack down on smuggling and stuff like that. So the war leads them to try to control the colonies more than ever before and the colonies don't like that.
2. Takes the French out of North America so the Americans don't have to worry about getting swallowed by France if they become independent.
3. Allows Americans from different colonies to get to know one another and see that they have things in common. Before that, they might as well have been from different countries so there was no way they'd work together to become independent.