John Quincy Marr was born May 27th 1825 in Warrenton, Fauquier, Virginia, the son of John and Catherine [Inman Horner] Marr. He graduated in 1846 from the Virginia Military Institute, the second in his class. After graduating Marr was the assistant professor of mathematics and tactics at VMI. When his father died in 1848 Marr returned home where he served for two years as the sheriff of Fauquier County, Virginia. Following John Brown’s Harpers Ferry raid in 1859, Marr helped organize the “Warrenton Rifles”, a local militia company.
Once the Civil War began Marr was commissioned Lieutenant Colonel on May 5th 1861 in the Confederate Army. A company of Union Cavalry entered Fairfax Court House on June 1st 1861, driving back Confederate pickets and taking prisoners. At the time the town was occupied by two companies of Confederate cavalry and Marr’s “Warrenton Rifles”. As the Confederate Cavalry began to retreat from Fairfax Court House, it left only about 40 of Marr’s men to fight the Union Cavalry.
The 2nd United States Cavalry led by Lieutenant Charles Henry Tompkins, with about 70 men in two groups road through the town. Marr was shot by a stray bullet and fell dead by the road side in a clover field. His death was not immediately known and his body wasn't found for several hours. Marr’s body was taken home to Warrenton where his funeral was attended by a large crowd.