John Erskine, the 23rd and 6th Earl of Mar and 1st Duke of Mar, KT, was a prominent Scottish nobleman and a key figure in the Jacobite movement. He held the title of the 23rd Earl of Mar from the earldom's first creation and was the sixth earl in its seventh creation. Erskine, often remembered for his political adaptability, navigated the complex and shifting landscape of early 18th-century British politics.

The Acts of Union were two Acts of Parliament: the Union with Scotland Act 1706 passed by the Parliament of England, and the Union with England Act 1707 passed by the Parliament of Scotland. They put into effect the terms of the Treaty of Union that had been agreed on 22 July 1706, following negotiation between commissioners representing the parliaments of the two countries. By the two Acts, the Kingdom of England and the Kingdom of Scotland—which at the time were separate states in a personal union—were, in the words of the Treaty, "United into One Kingdom by the Name of Great Britain".