[1] He was the son of Captain David Alexander Grant and Marie-Charles-Joseph Le Moyne, Baronne de Longueuil.
[1] He served during the War of 1812 as Lieutenant Colonel of the Boucherville militia battalion and as a staff officer.
He was taken prisoner by the Americans on 8 December 1813, and was held hostage in Worcester, Massachusetts.
[2][3] He succeeded to the title of Baron de Longueuil on 17 January 1841.
[1] He died on 5 July 1848[1][2] at his residence of Alwington House in Kingston.