The revolutionary period in Irish history was the period in the 1910s and early 1920s when Irish nationalist opinion shifted from the Home Rule-supporting Irish Parliamentary Party to the republican Sinn Féin movement. There were several waves of civil unrest linked to Ulster loyalism, trade unionism, and physical force republicanism, leading to the Irish War of Independence, the Partition of Ireland, the creation of the Irish Free State, and the Irish Civil War.

The Irish War of Independence or Anglo-Irish War was a guerrilla war fought in Ireland from 1919 to 1921 between the Irish Republican Army and British forces: the British Army, along with the quasi-military Royal Irish Constabulary (RIC) and its paramilitary forces the Auxiliaries and Ulster Special Constabulary (USC). It was part of the Irish revolutionary period.