Manitoba joined the Confederation as a proactive way to protect their rights and land. Canadians hoped to expand west to prevent the United States from expanding upwards and downwards, soon after the U.S. had purchased Alaska.
When the native people, the Metis, realized that Canadians would be moving into their land, they took control of Fort Garry and created a government with the intent of protecting their rights. They negotiated their rights with Sir John A. Macdonald, which turned into the Manitoba Act of 1870. With this act, Manitoba became a new province and a part of the Canadian Federation.