Ireland had undergone continual war since the rebellion of 1641, with most of the island controlled by the Irish Confederates. Increasingly threatened by the armies of the English Parliament after Charles I's arrest in 1648, the Confederates signed a treaty of alliance with the English Royalists. The joint Royalist and Confederate forces under the Duke of Ormonde tried to eliminate the Parliamentary army holding Dublin by laying siege, but their opponents routed them at the Battle of Rathmines (2 August 1649). As the former Member of Parliament Admiral Robert Blake blockaded Prince Rupert's fleet in Kinsale, Cromwell could land at Dublin on 15 August 1649 with an army to quell the Royalist alliance.