Queen Elizabeth II's visit to the Republic of Ireland
Queen Elizabeth II of the United Kingdom and her husband Prince Philip, Duke of Edinburgh, made a state visit to the Republic of Ireland from 17 May to 20 May 2011, at the invitation of the President of Ireland, Mary McAleese.
It was the first visit by a British monarch to the area that is now the Republic of Ireland since the 1911 tour by Elizabeth's grandfather King George V, when the entire island of Ireland was still part of the United Kingdom of Great Britain and Ireland.
The intervening period saw the 1916 proclamation of the Irish Republic during the Easter Rising against British rule in Ireland. A military conflict from January 1919 led ultimately to the partition of Ireland in December 1922. Northern Ireland remained part of the United Kingdom, while the Irish Free State (renamed Ireland in 1937) became a self-governing and then fully independent Dominion within the British Commonwealth. In 1949, the Irish state withdrew from the Commonwealth and abolished its last links to the monarchy on the formal declaration of the Republic of Ireland.
...
Wikipedia