When his elder brother died, John Murray as his father's heir, became Viscount Fincastle. As an Ensign he served at the battle of Blenheim in 1704. He was Brigadier General when Vigo was captured in 1719, and served in Flanders in 1732. In 1743 he was at the Battle of Dettingen where he was made a Knight Banneret by the king.
In 1713 and 1714 he was a Representative Peer and again from 1727 until 1752. From 1731 until 1752 he was Lord of the Bedchamber and Governor of Plymouth from 1745 until 1752. He was sixty-seven years old when he died in London on 18 April 1752 and, as he was unmarried, it was a younger brother who as his heir succeeded him. In 1720 he had bought the manor of Stanwell in Middlesex and it was here that John Murray, 2nd Earl of Dunmore, was buried.

Source: Leo van de Pas