King James raised an army in Ireland, but was ultimately defeated at the Battle of the Boyne on 1 July 1690 against William of Orange. Bryan Magauran fought on James’s side during the battle. He was a captain in the infantry regiment of Colonel
Oliver O'Gara. Bryan's brother, Daniel Magauran, was a lieutenant (later a captain) in the same regiment. O'Gara was a member of the
Patriot Parliament of 1689 where he represented of
Sligo County. His regiment took part in an expedition of 1689 led by
Patrick Sarsfield to capture the Protestant-held town of
Sligo. In 1690 O'Gara commanded the Jacobite garrison at
Jamestown in
County Leitrim, repulsing an advance by a larger force of Williamite troops under
James Douglas. O'Gara served with his regiment at the
Battle of Aughrim, which ended in Jacobite defeat. Following the
Treaty of Limerick, O'Gara acted as a hostage until it was clear the terms had been honoured. It is likely that Bryan Magauran was at his side during all those events. He is later referred to as Colonel Magauran so he may have been promoted after the Boyne. Another Mág Samhradháin was a captain in the
infantry regiment of Colonel
Henry FitzJames (1st Duke of Albemarle in the
Jacobite peerage) under the command of Lieutenant-Colonel Thomas Corbet. His first name is not given but he was probably a relation of Brian Mág Samhradháin. ==Family and end of the Mág Samhradháin lordship==