In 1563 he became Lord Chancellor of Scotland. Though his sympathies were with the reformers, he took no part in the combination of Protestant reformers in 1565, but he headed the armed force which took possession of Holyrood palace in March 1566 to effect the assassination of David Rizzio, and the leading conspirators adjourned to Morton's house while a messenger was sent to obtain Queen Mary's signature to the "bond of security". The Queen, before complying with the request, escaped to Dunbar, and Morton and the other leaders fled to England. Having been pardoned, Morton returned to Scotland early in 1567, and with 600 men appeared before Borthwick Castle, where the Queen had taken refuge after her marriage to Bothwell. Morton attended the remarkable stand-off at the battle of Carberry Hill in June 1567, Mary's new husband, James Hepburn, 4th Earl of Bothwell offered to settle the matter by single combat. When Patrick, Lord Lindsay took up the challenge, Morton gave Lindsay the sword of his ancestor, Archibald Douglas, 5th Earl of Angus. Mary vetoed a fight, and surrendered. Morton took an active part in obtaining the consent of the queen, while she was imprisoned at Lochleven Castle, to her abdication in July 1567. When Mary escaped from Lochleven, he led the vanguard of the army which defeated her forces at the Battle of Langside in 1568, and he was the most valued privy counsellor of the Earl of Moray during the latter's brief term of office as Regent of Scotland.

Answer this question based on the article: James Hepburn's title was what?
4th Earl of Bothwell