The Kingdom of Canada was established in 1867 by the British North America act, which united several of the British colonies into a new kingdom, headed by a Viceroy appointed by Queen Victoria. The kingdom spread westward with the acquisition of the Hudson Bay Company's lands, and the joining of the Colony of British Columbia. The colony of Prince Edward's Island became a Kingdom in 1872, but shortly afterwards joined the Kingdom of Canada. The kingdom enjoyed generally good relations with the United States, though there were a few war scares. Relations began to sour in the lead-up to the Global War, and, when the Global War started, the two nations found themselves on opposite sides. The war was harsh on both sides, but ended with the Kingdom occupied by American forces in much of its territory, and Japanese in the northwest, and subsequently ceasing to exist.
The Kingdom was restored soon afterwards, when the North American Federation was formed, on October 9, 1949. The Kingdom of Canada became a member-state of the Federation.
The biggest change after that point was the secession of Quebec from Canada, as another member of the Federation, and the unification of the maritime provinces into the new Province of the Maritimes.
After October 9, 1989, there was talk of secession from the Federation (the Charter forbad secession for the first 40 years after ratification), but ultimately, the choice was made to remain within the Federation