Nephew of the second Earl of Dunmore, at fifteen years he was appointed page to Charles Edward Stuart (“Bonnie Prince Charlie”) and, with his father William Murray, was a participant in the Jacobite Uprising of 1745, after which the Murrays were placed under house arrest. After his father’s conditional pardon in 1750, he joined the British Army. In 1756, after the deaths of his uncle and father, John became the fourth Earl of Dunmore, and sat as a Scottish representative peer in the House of Lords from 1761 to 1774 and from 1776 to 1790.
Lord Dunmore served as royal governor of the Colony of Virginia from 25 September 1771 until his departure to New York in 1776; he continued to hold the position and to draw his pay until 1783, when American independence was recognised.
Having a contentious relationship with the colonial legislature, he dissolved and reconvened the House of Burgesses several times. On 23 March 1774, Patrick Henry’s “Give me Liberty, or give me Death!” speech at the Second Virginia Convention and the accompanying resolution calling for the formation of an armed resistance made Dunmore “think it prudent to remove some Gunpowder which was in a Magazine in this place.” Dunmore gave a key to Lieutenant Henry Colins, commander of H.M.S. Magdalen, and ordered him to remove the powder, provoking what became known as the Gunpowder Incident. At Williamsburg, on the night of 20 April 1775, royal marines loaded fifteen half barrels of powder (one half barrel = one keg) into the governor’s wagon intent on transporting it down the Quarterpath Road to the James River to be loaded aboard the British ship. This was discovered while underway, and local militia rallied to the scene, and riders spread word of the incident across the colony.
Confronted by Patrick Henry and the Hanover Militia on 3 May, Lord Dunmore evacuated his family from the Governor’s Palace to his hunting lodge Porto Bello on the York River.
On 6 May, Dunmore issued a proclamation against “a certain Patrick Henry… and a Number of deluded Followers” who had organised “an Independent Company… and put themselves in a Posture of War.”
As hostilities continued, Dunmore himself left Williamsburg on 8 June 1775, retreating to Porto Bello where he joined his family. From there, being dislodged by the Virginia rebels and wounded in the leg, he took refuge on the British warship Fowey in the York River. General George Washington commented in December 1775, “I do not think that forcing his lordship on shipboard is sufficient. Nothing less than depriving him of life or liberty will secure peace to Virginia, as motives of resentment actuate his conduct to a degree equal to the total destruction of that colony.”
Dunmore is noted for Lord Dunmore’s Proclamation, also known as Lord Dunmore’s Offer of Emancipation, published on 7 November 1775, whereby he offered freedom to slaves who abandoned their Patriot masters to join the British forces. This was the first mass emancipation of slaves in North America. As governor of Virginia, Dunmore had withheld his signature from a bill against the slave trade. However, by the end of the War, an estimated 100,000 escaped slaves sought refuge with the British, an estimated 20,000 of them served in the army, though the majority served in noncombatant roles.
He organised these Black Loyalists into the so-called Ethiopian Regiment. However, after the Battle of Kemp’s Landing, Dunmore became overconfident, which precipitated his defeat at the Battle of Great Bridge, 9 December 1775. Following the defeat at Great Bridge, he loaded his troops, and many Virginia Loyalists, onto British ships; as there was an outbreak of smallpox at the time, this had disastrous consequences, particularly for the ex-slaves; some 500 of the 800 members of the Ethiopian Regiment died.
On News Year’s Day in 1776, after burning some buildings on the Norfolk waterfront from which the rebels were firing on his ships (ultimately giving them an excuse to burn the entire city), it became obvious that his position in Virginia was untenable and he retreated to New York.
From 1787 to 1796, he served as royal governor of the Bahamas.
Dunmore County was organised in 1772 and named in his honour, but as the American Revolution got underway, it was renamed Shenandoah County.