He was raised and educated in Tennessee, studying at Cumberland University before being nominated to the United States Military Academy at West Point from the Memphis district.

[1] In the autumn of 1852, Wilcox was ordered back to West Point to serve as assistant instructor of military tactics, a position he held until the summer of 1857, when, on account of failing health, he was sent to Europe on a twelve-month furlough.

On October 21, he was promoted to brigadier general and placed in command of a brigade comprising the 3rd Alabama, 1st Mississippi, and 1st Virginia infantry regiments along with an artillery battery.

On the battle's second day, July 2, his charge against a weakened Union line was met (and held off) by a suicidally brave countercharge from the 1st Minnesota Volunteer Infantry.

Heavy Union artillery fire, particularly from the guns on Cemetery Ridge under the command of Lt. Col. Freeman McGilvery, readily broke up Wilcox's assault, who ordered the brigade to withdraw.

For the rest of the war, Wilcox's Division saw heavy fighting, from the Overland Campaign through Appomattox Court House.

During the final days of the Siege of Petersburg in 1865, Wilcox's last-ditch stand on April 2 at Fort Gregg helped delay the Union forces long enough for Longstreet to maneuver into position to cover the army's retreat to the west.

After the close of the American Civil War, Wilcox was offered a command as a brigadier general in the Egyptian Army, but he declined it.

In 1886 U.S. President Grover Cleveland appointed Wilcox as chief of the railroad division for the government at Washington, D.C., and he served in that capacity until his death.