Noble and Soldier. Although born in England, Hamilton was the son of James Hamilton, the 2nd Marquess, whom he succeeded in 1625. He was educated at Exeter College, Oxford, and was appointed to the Scottish civil service in 1628 by King Charles I (1600 - 1649). He led an unsuccessful expedition in support of Gustavus Adolphus in Germany (1631-4). He became his King's chief advisor in Scotland and tried to negotiate with the Covenanters, but failing, he led a force against them in 1638. He was created Duke of Hamilton in 1643. A supporter of the Royalist cause, he secured the support of the Scottish Parliament for Charles, which led to a Scottish Army invading Cromwell's England. However, Hamilton was captured at the Battle of Preston, tried by the same court which had condemned his King and executed in London.
