The Treaty of Paris signed in 1763, was the end of the "French-Indian war", a conflict which took place among three major powers at the time : France, Britain and Spain which fought for the colonies in North America. These powers had Native American tribes allied with each one of them and it is called "French - Indian War" because the British considered the French and the Natives to be their enemies.
Spain might have contemplated this as a victory as it expanded its territories to the east, adding territories to their already vast empire of South and Central America. France basically lost their territories in North America,and their interest of exploiting natural resources such as furs. Finally, although British and Americans expanded their territories to the west, this entreprise was greatly expensive for Britain.
The utiliritarianism is an theory that asserts that you have to do what benefits the greatest number of people. If you kill someone that is a danger to society in order to protect other people, you will be doing what is ethic in that situation.