Glengarry's haughty and flamboyant personality, as expressed in his character and behaviour, gave Walter Scott the model for the wild Highland clan chieftain Fergus Mac-Ivor in the pioneering 1810 historical novel Waverley.

[2] In February 1793, after war with France had begun, Macdonell was commissioned as a captain to recruit a company of the Strathspey Fencibles, raised by Sir James Grant, a kinsman.

The boat-shaped cap without a peak is made of thick-milled woollen material with a toorie (or bobble) on the top and ribbons hanging down behind, capable of being folded flat.

In 1824 Glengarry unsuccessfully attempted to wrest the chiefship of Clan Donald from Ranald George Macdonald by bringing an action in the Court of Session.

He continued the evictions to make way for sheep farmers which his mother began when his father was chieftain, and most of the clan was forced to emigrate to British North America, as part of what was later known as the Highland Clearances.

His life was in stark contrast to his contemporary relative Bishop Alexander MacDonell who did missionary duty in Lochaber and tried to help his clansmen displaced by the substitution of sheep-farms for smallholdings to get employment in the Lowlands.

As Brian Osborne records, "In Edinburgh Sir Walter Scott was moved to compose Glengarry's Death Song, an undoubted expression of his genuine affection for the dead chief, if not perhaps a work of the greatest literary quality".

Their children were a son, Aeneas Ranaldson, born on 29 July 1808, and seven daughters, Elizabeth, Marcelly, Jemima Rebecca, Louisa Christian, Caroline Hester, Gulielmina Forbes, and Euphemia Margaret.