In 1964, the prime minister of Canada, Lester B. Pearson, introduced plans to replace the Union Flag with a new national flag, spurring the Great Canadian Flag Debate. The new maple leaf flag was approved by the Parliament of Canada on 17 December 1964. However, on the following day, the Canadian parliament passed another resolution that designated the Union Flag as the "Royal Union Flag", and authorized its official use as the symbol of the country's membership in the Commonwealth of Nations, and its allegiance to the Crown. The move was a concession given to those who preferred to adopt the Canadian Red Ensign as a formal national flag. On 15 February 1965, the maple leaf flag formally replaced the Union Flag as the flag of Canada following an official proclamation by Elizabeth II; with the Royal Union Flag made an official ceremonial flag.