James was a younger brother of
Robert Stewart, 1st Lord Lorne (1382–1449), whose descendants bore this title. He was an ally of the Black Douglases,
Earls of Douglas. After the murder of
James I of Scotland in 1437, power was held by
Archibald Douglas, 5th Earl of Douglas as
regent for the underage
James II of Scotland. The Stewarts of Lorne were amongst his most trusted supporters, and their power greatly increased while the
Douglas family controlled Scotland and the king was a mere 7 years of age. However, the unexpected death of the 5th Earl of Douglas from a fever in 1439 saw power now being uneasily shared between
William, 1st Lord Crichton,
Chancellor of Scotland and Sir
Alexander Livingston, Governor of
Stirling Castle. Stewart married
Joan Beaufort, the queen consort, and became stepfather to James II. Stewart and his Douglas allies planned to remove the young James II, who was being held by Livingston in his stronghold of Stirling Castle. However, Livingston arrested Lady Joan on 3 Aug 1439, imprisoning her in Stirling Castle, while throwing Sir James and his brother Sir William into its dungeon. They were later released on good behaviour. Stewart was given safe conduct to England in 1445, 1447 and 1451. He was supposedly captured at sea by
Flemish pirates and put to death after 1451. But he was still alive in 1453–54, when he carried King James II's offer to Joan’s brother
Edmund Beaufort, Duke of Somerset to rescue him from the Tower of London, when Somerset was a prisoner during the regency of Richard Duke of York. ==Family==