The Irish War of Independence (Irish: Cogadh na Saoirse, also known as the Anglo-Irish War or Tan War) was a guerrilla war mounted against the British government in Ireland by the Irish Republican Army (IRA). It began in January 1919, following the Irish Republic's declaration of independence, and ended with a truce in July 1921. The subsequent negotiations led to the Anglo-Irish Treaty, which ended British rule in most of Ireland and established the Irish Free State. However, six northern counties would remain under British rule.

The IRA that fought in this conflict is often referred to as the Old IRA to distinguish it from later organisations that used the same name.

Origins