Background
He was the son of Randal MacDonnell, 1st Earl of Antrim and his wife, Alice O"Neill (Alice was the daughter of Hugh Ó Neill, 2nd Earl of Tyrone).
He was the son of Randal MacDonnell, 1st Earl of Antrim and his wife, Alice O"Neill (Alice was the daughter of Hugh Ó Neill, 2nd Earl of Tyrone).
When the first Earl died in 1636 his estate was divided, with the larger share and Dunluce Castle going to the elder brother Randal while Alexander inherted Glenarm Castle and nearby lands. After coming of age, MacDonnell spend three years abroad in Europe before returning to Ireland just before the outbreak of the Irish Rebellion of 1641. MacDonnell was commander of a regiment of Irish against Cromwell in 1641, and soon took his place among the Irish leadership.
He remained in command of a regiment until the Confederation surrendered to Cromwell in 1652.
His lands were confiscated and distributed amongst Cromwellian soldiers. By 1656, MacDonnell was living in England, and at Restoration was restored to his lands.
At the outbreak of the Glorious Revolution, MacDonnell adhered to James and presided over the unsuccessful siege of Derry. On James"s defeat, MacDonnell"s lands and titles were, again, declared forfeit.
In 1697 he was restored to his title.
MacDonnell"s residence was at Glenarm Castle on the County Antrim coast. She died childless in 1669.
