The French and Indian War was the North American part of a much larger war raging in the mid-Eighteenth Century called the Seven Years War. The Empires of Britain and France were struggling for control of multiple areas around the world. In North America, that struggle raged for 5 years in actions ranging from isolated skirmishes to full scale invasions.
Quebec would be the primary prize for the armies and its fall would mean the almost guaranteed defeat of New France.