The French and Indian War was largely caused by competing claims over land in North America between the French and English, as well as the encroachment of English settlers into the area that is now Ohio. This encroachment led to French expeditions to reassert control.
France attacked first and the colonies responded, ultimately requiring England to intervene with additional soldiers and supplies. The war itself nearly doubled the English national debt and left England looking for ways to increase revenue. It sought to do this through additional taxes on the American colonies, which proved to be unpopular and led to some unrest. England's response was to send in troops to reassert control, but this move gave more traction to the revolutionaries and ultimately led to the Revolutionary War.