George Mackay, 3rd Lord Reay (born in 1678 and died in 1748) was a Scottish noble and chief of the Clan Mackay, a Scottish clan of the Scottish Highlands. During his life the Glorious Revolution took place which directly affected his family and estate, and during his chiefdom he served the British-Hanoverian Government during the Jacobite rising of 1715 and the Jacobite rising of 1745.
George Mackay, 3rd Lord Reay was the only son of Donald Mackay, Master of Reay and his wife Ann, daughter of Sir George Munro of Culrain (of Newmore). The Master of Reay was killed in an accident in 1680 when a barrel of gunpowder exploded whilst hunting in the Reay Forest, and his father, John Mackay, 2nd Lord Reay, died not long after. George Mackay, 3rd Lord Reay therefore succeeded his grandfather the 2nd Lord Reay.
The period of 1680 – 1688 was of growing religious persecution in Scotland with the House of Stuart steering for political perdition.Charles II of England died in 1685 and was succeeded by his brother James II of England and VII of Scotland. James roused the Scots Covenanters to desperation and also alienated himself from many of the Cavalier families, until finally in 1688 the Stuarts were overthrown in the Glorious Revolution and replaced by William of Orange. The Mackay's lands of Strathnaver had offered asylum to persecuted Covenenters and John Mackay, 7th of Aberach, chieftain of the Mackay of Aberach branch of the clan had also supported the Covenenters.
A Jacobite rising broke out in 1689 in support of the exiled Stuarts and a Mackay clansman, General Hugh Mackay of Scoury was appointed by William of Orange as Commander-in-Chief of the forces in Scotland. Hugh Mackay was defeated by the Jacobites at the Battle of Killiecrankie although the Jacobite leader John Graham, 1st Viscount Dundee was killed in the battle. This Jacobite rising was ultimately defeated at the Battle of Dunkeld and the Battle of Cromdale the following year in 1690. General Hugh Mackay went on to support William of Orange during the Williamite War in Ireland and was killed at the Battle of Steenkerque in Belgium in 1692. In 1693 or 1694, shortly after the death of his grandfather Sir George Munro of Culrain, the young George Mackay, 3rd Lord Reay travelled over to Holland where his two uncles Aneas and Robert Mackay were on service as Lieutenant-General and Colonel. One of these uncles died in 1696 and the other in 1697. According to historian Angus Mackay at this time a strong stream of Strathnaver men (Mackays) flowed abroad as soldiers of fortune and some were on the ill-fated Darien scheme.