The Treaty of Paris of 1763 ended the French and Indian War/Seven Years' War between Great Britain and France, as well as their respective allies. In the terms of the treaty, France gave up all its territories in mainland North America, effectively ending any foreign military threat to the British colonies there.
It was Great Britain. You can see it through the fact that English is still spoken there. Southern Rhodesia is today's Zimbabwe and Northern Rhodesia is today's Zambia.
