The Flight of the Earls took place on 14 September 1607, when Hugh Ó Neill of Tír Eóghain, Rory Ó Donnell of Tír Chonaill and about ninety followers left Ireland for mainland Europe.
After their defeat at the Battle of Kinsale in 1601, and the suppression of the Nine Years' War in Ulster in 1603, Tyrone and the Prince of Tyrconnell, Lord Tyrconnell's elder brother and predecessor, had been forced into exile in January 1602 by the victorious English government of Ireland under the leadership of the Lord Mountjoy. They retained their lands and titles, although with much diminished extent and authority. However, the countryside was laid bare in a campaign of destruction in 1602, and induced famine in 1603, in the same way that O'Neill had devastated Munster in 1600. O'Neill was pardoned under the terms of the Treaty of Mellifont in March 1603 and submitted to the crown.
When King James I took the throne in 1603 he quickly proceeded to issue pardons for the Irish lords and their rebel forces. As king of Scotland he had a better understanding of the advantages of working with local chiefs in the Scottish Highlands. However, as in other Irish lordships, the 1603 peace involved O'Neill losing substantial areas of land to his cousins and neighbours, who would be granted freeholds under the English system, instead of the looser arrangements under the former Brehon law system. This was not a new policy but was a well-understood and longstanding practice in the Tudor conquest of Ireland.
By 1607 O'Neill's allies The Maguire and the Earl of Tyrconnell were finding it hard to maintain their prestige on lower incomes. The earls left from the town of Rathmullan on Lough Swilly on a French ship with some of the leading Gaelic families in Ulster. This town was said to have witnessed the end of the old Gaelic order, in the sense that the earls were descended from Gaelic clan dynasties that had ruled their parts of Ulster for centuries. The Flight of the Earls was a watershed in Irish history, as the ancient Gaelic aristocracy of Ulster went into permanent exile. Despite their attachment to and importance in the Gaelic system, the Earls' ancestors had also accepted their Earldoms from the English-run Kingdom of Ireland in the 1540s, under the policy of surrender and regrant. Some historians argue that their flight was forced upon them by the fallout from the Tudor conquest of Ireland, others that it was a strategic mistake that cleared the way for the Plantation of Ulster.