Question

Why is William Pitt so important ?

Answer 1

the driving force behind the British victory in the Seven Years War, known as the French and Indian War in North America.

Answer 2

Well he did a lot of things , here's one :
He organized the eventual British victory in the French and Indian War, in 1763 which lead to the elimination of the French from North America, and the acquisition of Canada , Louisiana east of the Mississippi and Florida.