The Nine Years' War, sometimes called Tyrone's Rebellion, took place in Ireland from 1593 to 1603. It was fought between an Irish confederation—led mainly by Hugh O'Neill of Tyrone and Hugh Roe O'Donnell of Tyrconnell—against English rule in Ireland, and was a response to the ongoing Tudor conquest of Ireland. The war began in Ulster and northern Connacht, but eventually engulfed the entire island. The Irish alliance won numerous victories against the English forces in Ireland, such as the Battle of Clontibret (1595) and the Battle of the Yellow Ford (1598), but the English won a pivotal victory against the alliance and their Spanish allies in the siege of Kinsale (1601–02). The war ended with the Treaty of Mellifont (1603). Many of the defeated northern lords left Ireland to seek support for a new uprising in the Flight of the Earls (1607), never to return. This marked the end of Gaelic Ireland and led to the Plantation of Ulster.

Hugh O'Neill, Earl of Tyrone was an Irish Gaelic lord and key figure of the Irish Nine Years' War. Known as the "Great Earl", O'Neill led the coalition of Irish clans against the English Crown in resistance to the Tudor conquest of Ireland under Queen Elizabeth I.