The Kingdom of Ireland was a major source of concern and expense during Robert Cecil's time in government. The Nine Years' War there had ended with the leader of the rebels, Hugh O'Neill, Earl of Tyrone, submitting to the Crown and being restored to his estates, following the Treaty of Mellifont (1603). Four years later, Tyrone had led his followers into exile during the Flight of the Earls. The response of the government was to plan a Plantation of Ulster, to share out Tyrone's lands between the Gaelic Irish lords and the settlers from Britain. In 1608, Sir Cahir O'Doherty launched O'Doherty's rebellion by attacking and burning Derry. In the wake of O'Doherty's defeat at Kilmacrennan, a much larger plantation was undertaken.