"Naturalisation is the process by which one undertakes allegiance to a new sovereign and, often enough, sheds allegiance to another sovereign." Between 26 January 1949 and 30 November 1973, British subjects were able to apply for registration as an Australian citizen after one year's residence in Australia as an immigrant, and there was no requirement to attend a citizenship ceremony. Non-British subjects were required to apply for naturalization, which had stricter requirements, including a five-year residency. They were required to attend a citizenship ceremony and swear an oath of allegiance to the Crown. From 1966 they were also obliged to renounce "all other allegiance".