His grandfather and namesake, Col. Francis Mallory (1740-1781) was a Virginia militia officer who married three times before his death in the Skirmish at Waters Creek while defending Hampton during the Patriot's Siege of Yorktown near the end of the American Revolutionary War.
He attended the private Hampton Academy and began a career as a naval officer after his father's death in Norfolk in 1820, accepting a midshipman's commission in the United States Navy and serving from 1822 to 1828.
He also served as Navy Agent in Norfolk during the administration of President Millard Fillmore (a fellow Whig) in the early 1850s.
In 1853, the new railroad hired a 26-year-old civil engineer and Virginia Military Institute graduate from Southampton County named William Mahone.
He designed and implemented an innovative corduroy roadbed through the Great Dismal Swamp between South Norfolk and Suffolk.
The design included a log foundation laid at right angles beneath the surface of the swamp, and rented enslaved labor built it.
Mahone was also responsible for engineering and building a 52 mile-long tangent track between Suffolk and Petersburg which remains a major artery of modern Norfolk Southern rail traffic (although rebuilt after the American Civil War).