War Of Spanish Succession. Whitehall 6 April 1714. Secretary of States Letter appointing George Hamilton The Earl of Orkney to be Governor of Edinburgh Castle. Signed by Francis Gwyn Secretary of War. Size 7” × 8½”. Field Marshal George Hamilton, 1st Earl of Orkney KT ( 1666 – 1737), was a British soldier and Scottish nobleman and the first British Army officer to be promoted to the rank of field marshal. After commanding a regiment for the cause of William of Orange during the Williamite War in Ireland, he commanded a regiment in the Low Countries during the Nine Years' War. He led the final assault at the Battle of Blenheim with eight battalions of men and then receiving the surrender of its French defenders during the War of the Spanish Succession. Also led the charge of fifteen infantry battalions in an extremely bloody assault on the French entrenchments at the Battle of Malplaquet. In later life he became a Lord of the Bedchamber to George I and was installed as Governor of Edinburgh Castle. Francis Gwyn (1648 – 1734), was a Welsh politician and who held a number of official positions and was a close associate of the Earl of Rochester.