Smyth was born on Rathlin Island in County Antrim (part of the Kingdom of Ireland).

Alfred Smythe at the age of 10, and settled in Botetourt County, Virginia, in 1775 where he completed preparatory studies.

Commissioned as a colonel in 1808, he served as Inspector General to William Eustis, the acting War Secretary.

His plan to invade Canada started with the Battle of Frenchman's Creek but was then abandoned because of problems due to poor organization.

[4] After the war, Smyth resumed the practice of law, and again became a member of the Virginia House of Delegates in 1816, 1817, 1826, and 1827.