Son of Angus and Mary McGuire McDonald. Graduated from West Point. Married 1-11-1827 to Anne Naylor. After her death he married Cornelia Peake. Angus and Edward Charles McDonald (brothers) were married to sisters. Edward was married to Susan Ellen Peake. Angus resided at "Hawthorne" near Winchester.

Organizer of the 7th Virginia Cavalry, CSA. Captain Turner Ashby made Lt. .Colonel on McDonald's recommendation to the War Dept.

His mother died when he was 10 years old. He was reared by his grandmother at "Glengarry" He attended Winchester Academy before going to West Point. He was a Third Lieutenant of Artillery and served at New Orleans and Mobile. He joined his brother in St. Louis to survey the lands in Iowa. He possessed an unusual degree of physical strength and was athletic and confident. He was a friend and interpreter to the Sioux, who admired and trusted him. They called him "Big Knife". He was regarded favorably by the Chiefs of some tribes, while those of others were his enemies. He became Captain of an Indian command that was part of the Missouri Legion. He was leader in the fight against the Aricaras. He moved to Romney, Virginia in 1824, where he studied Law, served as Deputy Sheriff and Coroner. He was admitted to the bar and accumulated a large amount of land. He became interested in railroading and was awarded patents for inventions for that industry. He was appointed to the Commission to resolve an old boundary dispute between Virginia and Maryland. He travelled to England to establish the true lines between Virginia, North Carolina, Tennessee and Maryland.