By the 1630s, the vast majority of Scots belonged to the Protestant Church of Scotland or kirk; Catholicism was confined to parts of the aristocracy, such as the Marquess and Lady Mary, and remote Gaelic-speaking areas of the Highlands.

The Covenanter government that ruled Scotland during the 1638-1651 Wars of the Three Kingdoms ordered the Douglas children to be brought up as Protestants; to escape this, George was sent to France and he first appears in a safe conduct pass dated 1647 giving him permission to do so.

[5] In this period, regiments were the personal property of their Colonel and valuable financial assets; in 1645, ownership passed to the Earl of Angus, who remained in Scotland and assigned the Colonelcy to Dumbarton in 1653.

[8] Dumbarton's troops were sent to England but the revolt was quickly crushed and they returned to France, since the Cavalier Parliament refused to finance replacements for the disbanded New Model Army; this would be an issue throughout Charles' reign.

[14] The Brigade fought primarily in the Rhineland, to avoid potential clashes with English and Scots serving with the Dutch; a large part of it was provided by Dumbarton, whose regiment was expanded to 33 companies or 3,432 men.

At the same time, the end of the Franco-Dutch War led to Dumbarton's regiment being discharged from the French army in June 1678; in January 1679, it was reformed and listed on the English military establishment as the 'First Foot.'

[19] As a Catholic military professional and long-time servant of Louis XIV, Dumbarton was viewed with great suspicion by the Whigs; he petitioned Charles for compensation for financial losses arising from the 1678 Test Act, which barred him from Colonelcy of his regiment.

[22] James was sent to Edinburgh in 1681 as Lord High Commissioner to the Parliament of Scotland; over the next two years, he established a Scottish Court Party, a mixture of Catholics like the Earl of Melfort and Dumbarton, plus supportive Protestants such as his brother, the Duke of Hamilton.

James became king in February 1685 and in June, Dumbarton helped put down Argyll's Rising; he served briefly as Commander-in-Chief, Scotland but was replaced in October by the Presbyterian William Drummond, Viscount Strathallan.