Born in Scotland about 1769, Miles emigrated with his father, 'Spanish' John, and other members of the family to New York 1773. Following the Revolution, they settled near Cornwall at St. Andrews West. In 1811-12 he became Lord Selkirk's agent, and led the first band of settlers to the Red River colony. The Nor'Westers endeavoured to destroy the settlement, and arrested Macdonell on a false charge in 1815. Released without trial, he returned to his farm in Osnabruck township, but later moved to his brother's residence at Pointe Fortune, where he died in 1828.