He began his career as a soldier in the Netherlands, where he became a colonel and entered into communications with Lord Burghley on the progress of affairs. In 1582 he was in Scotland, and James VI made him captain of his guard. He visited the English court in the king's interest in 1583 with John Colville and George Young. Later that year, Stewart helped to free James from William Ruthven, 1st Earl of Gowrie, and to bring back his cousin James Stewart, Earl of Arran to power; these acts largely restored the young King James's position, after the Raid of Ruthven. On 4 September 1583 at Falkland Palace James VI ordered that Colonel Stewart be given some of the jewels that had belonged to his mother Mary, Queen of Scots, including a gold cross previously given to his favourite, Esmé Stewart, 1st Duke of Lennox. He was made a privy councillor and assisted Arran in governing Scotland. In 1584 he captured Gowrie at Dundee. In 1585 he and Arran lost their power, and Stewart went to Denmark and France on secret errands for the king.
Norway and Denmark
Colonel Stewart became prominent in the king's marriage negotiations with Denmark, joining an embassy with Peter Young. In February 1588 an informant wrote to Francis Walsingham that Stewart had returned from Denmark with news of agreement that James VI should marry the younger daughter Anne of Denmark, according to the wishes of her mother Sophie of Mecklenburg-Güstrow, because she "thinks her most meet for him." He travelled to Norway in 1589 where the Danish fleet carrying Anne of Denmark rested. In December 1590 he returned to Scotland with instructions for the ruling council from James VI, including orders for ships for the king's return, the reception ceremony for the queen and repairs to Holyrood Palace. He arrived at Kronborg on 4 April with a letter to James VI from Queen Elizabeth. On 7 April 1590 he wrote from Helsingør to the English diplomat in Edinburgh, Robert Bowes. James VI had a valet in Denmark who was also called "William Stewart" and this was also the name of one of the captains of his fleet. He commanded the ships which conveyed James and his bride, Anne, from Denmark in April 1590. In June 1590 James VI of Scotland sent John Skene and Stewart as ambassadors to Denmark and Germany. The mission was to intended to cement a peaceful league in Europe. They met the mother of Anne of Denmark, Sophie of Mecklenburg-Güstrow at Braunschweig, then went on to meet William IV, Landgrave of Hesse-Kassel at Rotenburg an der Fulda and Christian I, Elector of Saxony at Dresden. In April 1591 the English ambassador Robert Bowes joked with Stewart over the lack of written responses the king had received.
Later life
In July 1592 he was questioned by the Chancellor, John Maitland of Thirlestane, the Secretary, Richard Cockburn, John Carmichael, and John Skene, about his dealings with Francis Stewart, 5th Earl of Bothwell. Stewart admitted that he had been in Edinburgh Castle playing cards with the imprisoned Earl of Bothwell shortly before Bothwell escaped on 21 June 1591, and denied that he had secret communications with Bothwell. Twice he went on missions to the Netherlands. In 1594 he was knighted and was given lands at Houston. John Wemyss of Logie heard in September 1595 that he had been in Mecklenburg and Braunschweig, where Christian IV of Denmark had travelled to meet his future wife, Anne Catherine of Brandenburg. He was sent on an embassy to Denmark in May 1598, escorting Ulrik, Duke of Holstein who had been travelling in England and Scotland, and returned in July. In February 1600 he encountered the Earl of Gowrie in a long gallery or passage in Holyrood Palace. He had arrested the earl's father in 1584. The earl made to move out of Stewart's way then reconsidered. Stewart noted this and complained to the king as an offence to his long service and dignity, warning that Gowrie was a threat to the court. Gowrie was told about this, and said "Aquila non captat muscus", meaning the eagle does not catch flies, that Stewart was beneath his attention. He died before 1606.
Family and children
Stewart married in 1582, Erica or Erika, Countess of Batenburg in Gelderland and Manderscheid, the widow of Willem van Bronckhorst-Batenburg. On 7 June 1590 he married Isobel Hepburn, Lady Pitferran, at Holyroodhouse. Anne of Denmark was godmother to his only son, Frederick. He was created a peer as Lord Pittenweem in 1609, and died childless in December 1625.
