He was born on 19 April 1785 in Scotland near Aberchalder and came to Canada when he was seven years old. There he studied to become a lawyer and was called to the bar at the age of 23, opening his own law office. An interest in politics earned him a seat on the legislature and an appointment as attorney-general. At the Redan Battery, a plaque mounted on a trio of large stones also serves as a monument to Macdonell. The plaque reads: Site of Redan Battery | Near this spot Lieut-Col. John Macdonell Attorney General of Upper Canada was mortally wounded 13 October 1812.