When King George VI died in February 1952, Princess Elizabeth became Queen Elizabeth II, Head of the Commonwealth and queen regnant of seven independent Commonwealth countries: the United Kingdom, Canada, Australia, New Zealand, South Africa, Pakistan, and Ceylon. She has reigned through major constitutional changes, such as devolution in the United Kingdom, Canadian patriation, and the decolonisation of Africa. Between 1956 and 1992, the number of her realms varied as territories gained independence and realms, including South Africa, Pakistan, and Ceylon (renamed Sri Lanka), became republics. Her many historic visits and meetings include a state visit to the Republic of Ireland and visits to or from five popes. Significant events have included her coronation in 1953 and the celebrations of her Silver, Golden, and Diamond Jubilees in 1977, 2002, and 2012 respectively. In 2017, she became the first British monarch to reach a Sapphire Jubilee. She is the longest-lived and longest-reigning British monarch as well as the world's longest-reigning queen regnant and female head of state, the oldest and longest-reigning current monarch and the oldest and longest-serving current head of state.