The Battle of Curlew Pass was fought on 15 August 1599 during the campaign of the Earl of Essex in the Nine Years' War, between an English force under Sir Conyers Clifford and a rebel Irish force led by Hugh Roe O'Donnell. The English were ambushed and routed while marching through a pass in the Curlew Mountains, near the town of Boyle, in the west of Ireland. The English forces suffered heavy casualties. Losses by allied Irish forces were not recorded but were probably minimal.