Harry W. Gilmor (January 24, 1838 – March 4, 1883) served as the Baltimore City Police Commissioner, head of the Baltimore City Police Department in the 1870s, but he was most noted as a daring and dashing Confederate cavalry officer during the American Civil War. Gilmor's daring raids, such as The Magnolia Station Raid through north-central Maryland in July 1864 during the third major Confederate invasion of the North gained his partisans fame as "Gilmor's Raiders".
Gilmor was born at "Glen Ellen", the Jacobethan/English Tudor-styled "Castle" family estate, near the village of Warren, (now beneath the surface waters of the Loch Raven Reservoir), just north of Towsontown in central Baltimore County, Maryland. He was the son of Robert Gilmor and Miss Ellen Ward, daughter of Judge William H. Ward. Harry was the fifth of eleven children.
During the American Civil War, as a member of the "Baltimore County Horse Guards" under Captain Charles Carnan Ridgely, Jr.'s (of Hampton Mansion, near Towsontown), Gilmor was arrested and imprisoned in Fort McHenry following the "Pratt Street Riots" of April 19th, 1861, with the subsequent occupation of Baltimore and Fort Federal Hill by Federal troops under Gen. Benjamin F. Butler of the 6th & 8th Massachusetts state militia in May 1861. Upon his release, he traveled South and eventually rejoined the fighting serving, for a while, under General Turner Ashby. He was again captured during the Maryland Campaign and spent five months in prison. During the Gettysburg Campaign of June–July, 1863, Major Gilmor was assigned command of the First Maryland Cavalry and Second Maryland Cavalry, supporting Brig. Gen. George Steuart's infantry brigade. Gilmor was the provost marshal of the town of Gettysburg while it was occupied by the Confederates July 1–4.