Born in Alabama, Davis was the eldest of six sons born to Benjamin E. and Matilda Holladay Davis between 1831 and 1843. Matilda Davis dies in 1843. Benjamin E. Davis died in June 1846. 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. Davis was originally assigned to the 5th U. S. Infantry but transferred to the 1st. U. S. Dragoons March 3, 1855. Wounded while fighting the Apache in frontier New Mexico, Davis served with the dragoons in New Mexico and California. He was a captain with the 1st Dragoons when he was appointed Lt. Colonel of the 1st California Volunteer Cavalry Battalion on August 19, 1861. He commanded this battalion until he resigned on November 1, 1861 to return east with the 1st U.S. Cavalry. At the outbreak of war Davis decided to stay with the Union, and was promoted to captain, 1st U.S. Cavalry Regiment, July 30, 1861. Davis had three brothers who served in the Confederate States Army two with the 11th Mississippi Infantry; and a third in the 2nd Mississippi. Neither brother who served with the 11th Mississippi survived the war. The brother who served with the 2nd Mississippi survived the war but took his own life several years after hostilities ceased. Commissioned colonel of the 8th New York Volunteer Cavalry 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. Finding his commanding officer Col. Dixon S. Miles unable to protect the force from bombardment and ready to surrender his troops, Davis and fellow officer Lt. Col. Hasbrouck Davis with his 12th Illinois Cavalry determined to fight their way out northward out of the encirclement. Crossing the Potomac River on a pontoon bridgeunder cover of night, 1,300 Union cavalrymen quietly escaped, overwhelming or avoiding Confederatepickets assigned to cover the winding road north. While moving in pitch black darkness, Davis came across an artillerywagon train belonging to Confederate Maj. Gen. 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. Davis was promoted to major, U.S. Army, for his exploit. Davis led the 1st Brigade of Brig. Gen. Alfred Pleasonton's cavalry division through the ineffectual "Stoneman Raid" in the Chancellorsville Campaign. In the Gettysburg Campaign, Davis led the brigade in the Battle of Brandy Station. 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. Davis himself refused to fall back and challenged all comers to combat. He twirled his saber with one hand, firing his Colt revolver with the other until he ran out of ammunition. Confederate Lt. O. R. Allen of Major Caball E. Flournoy's regiment charged at Davis, hugging his horse's neck to evade Davis's saber slashing, then fired his pistol three times at point-blank range. The third shot struck Davis in the forehead, killing him instantly. Davis was a man of rough manners and a stern disciplinarian. One of his troopers described him as "a proud tyrannical devil" as likely to be killed by his own soldiers as by the Confederates. The Provost Marshal General of the Army of the Potomac, Marsena R. Patrick, described him as "our best cavalry officer". He was buried in the West Point cemetery.
