Which European power fought against Britain in the French and Indian War? France fought against Britain in the French and Indian War. The conflict was an imperial struggle for control of territory and trade in North America, especially the Ohio Country and the waterways connecting the Great Lakes, the Mississippi basin, and the Atlantic colonies.
France's North American forces included troops from the French army and naval service, Canadian militia, and Indigenous allies. Britain relied on regular soldiers, colonial provincial forces, and Indigenous nations aligned with British interests. The war was therefore not simply a two-sided European contest; Native diplomacy, military alliances, and territorial interests were central to its course.
The war began in North America in 1754 and became part of the global Seven Years' War, which formally expanded in Europe in 1756. France suffered major defeats after Britain's wartime leadership shifted under William Pitt. British victories at Louisbourg, Quebec, and Montreal eventually ended effective French control of Canada.
The Treaty of Paris in 1763 required France to cede Canada and most of its mainland North American possessions to Britain. Spain entered the wider conflict on France's side late in the war, but Spain was not the principal European opponent in the French and Indian War. That is why France is the canonical answer to this question.