May 1 – Charles II repudiates his alliance with Irish Catholics in favour of one with Scottish Covenanters in the Treaty of Breda. Most English Royalists in Ireland surrender to the Parliamentarians after this point.
May 17 – Siege of Clonmel: Cromwell's troops storm the walls, taking up to 2,500 casualties. Although they are unable to take the town by force, the garrison, without supplies, slips away under cover of darkness.[2]
^ abPlant, David (2008-02-29). "1650: The Siege of Clonmel". British Civil Wars, Commonwealth and Protectorate 1638–60. Archived from the original on 2012-07-17. Retrieved 2013-06-20.