Fenians were members of a mid-19th century movement to secure Ireland’s independence from Britain. They were a secret, outlawed organization in the British Empire, where they were known as the Irish Republican Brotherhood. They operated freely and openly in the United States as the Fenian Brotherhood. Eventually, both wings became known as the Fenians. They launched a series of armed raids into Canadian territory between 1866 and 1871. The movement was primarily based in the United States, but it had a significant presence in Canada.