Elizabeth II (born 1926) is the constitutional monarch of 16 sovereign states known as the Commonwealth realms, head of the 54-member Commonwealth of Nations, and head of state of the Crown Dependencies and British Overseas Territories. Her father, George VI, acceded to the throne in 1936 on the abdication of his brother Edward VIII. She began public duties during the Second World War, in which she served in the Auxiliary Territorial Service. On George VI's death in 1952, she became Head of the Commonwealth and Queen of seven independent Commonwealth countries: the United Kingdom, Canada, Australia, New Zealand, South Africa, Pakistan, and Ceylon. Her coronation service in 1953 was the first to be televised. Since her accession, the number of her realms has varied as territories gained independence and some realms became republics. In 1947 she married Prince Philip, Duke of Edinburgh, with whom she has four children: Charles, Anne, Andrew, and Edward. Her reign of 72 years is the second-longest for a British monarch; only Queen Victoria has reigned longer. Elizabeth's Silver and Golden Jubilees were celebrated in 1977 and 2002; her Diamond Jubilee is being celebrated during 2012.