 By 1650, the Irish Confederates and their English Royalist allies had been driven out of eastern Ireland by the Cromwellian conquest of Ireland.They defended the line position behind the River Shannon, of which Limerick was the southern stronghold.Oliver Cromwell himself had left Ireland in May 1650, delegating his command of the Parliamentarian forces in Ireland to Henry Ireton, who sent Hardress Waller to take Limerick.