First introduced by Thomas Francis Meagher in 1848, it was not until the Easter Rising of 1916, when it was raised above the General Post Office in Dublin, that the tricolour came to be regarded as the national flag. The flag was adopted in 1919 by the Irish Republic during its war of independence, and subsequently by the Irish Free State (1922–1937), later being given constitutional status under the 1937 Constitution of Ireland. The tricolour is regarded by many nationalists as the national flag of the whole of island of Ireland. Thus it is flown (often controversially) by many nationalists in Northern Ireland as well as by the Gaelic Athletic Association. Historically the island has been represented by a number of other flags, including Saint Patrick's cross, and the flag of the four provinces of Ireland.