The Irish War of Independence (Irish: Cogadh na Saoirse) or Anglo-Irish War was a guerrilla war fought from 1919 to 1921 between the Irish Republican Army (the army of the Irish Republic) and the British security forces in Ireland. It was an escalation of the Irish revolutionary period into armed conflict.In the December 1918 election, the Irish republican party Sinn Féin won a landslide victory in Ireland.