Benjamin Davis and his five younger brothers became wards of an uncle, William Taylor, who lived in Monroe County, Mississippi.

Davis was appointed from Mississippi to the United States Military Academy at West Point, New York, graduating in 1854.

Among his classmates were Jeb Stuart, Stephen H. Weed, Oliver Otis Howard and William Dorsey Pender.

Commissioned colonel of the 8th New York Cavalry Regiment on June 25, 1862, Davis was leading that unit on September 14, stationed with the defending force at Harpers Ferry, after the town had been invested by troops under Stonewall Jackson.

While moving in pitch black darkness, Davis came across an artillery wagon train belonging to Confederate Major General James Longstreet, and using his deep Mississippi-accented voice, ordered their unsuspecting commander to change direction and accept his unit as cavalry escort.

As sunlight broke, the wagon drivers were startled to discover drawn pistols from their blue-clad escort, and as a result Davis's command not only escaped to Union lines at Greencastle, Pennsylvania, by morning September 15, but also captured Longstreet's forty-wagon reserve ordnance train with no losses.

In the early hours of June 9, 1863, Davis's men charged a South Carolina artillery battery near Beverly's Ford and were met by a strong cavalry counterattack, which sent most of the brigade reeling.