Harry Gilmor was born January 24, 1838 at "Glen Ellen", the family estate in Baltimore County, Maryland. After homesteading in Wisconsin and Nebraska, he returned to Maryland in time to join the newly formed Baltimore County Horse Guards as a corporal.

After the efforts of the citizens of Baltimore to prevent the movement of Federal troops through the city, the Horse Guards received orders to burn several bridges north of the city to prevent further troop movements toward Washington City.

Following the occupation of Baltimore by Federal troops under Brigadier General Benjamin "Beast" Butler, Gilmor was one of many to be arrested and imprisoned in Fort McHenry. After his release, he traveled South and joined the command of Colonel Turner Ashby on August 31, 1861.

In March 1862, he was commissioned Captain of Company F, Twelfth Virginia Cavalry. Captain Gilmor served throughout the Valley Campaign. At times, he was on special assignment to General Thomas J. "Stonewall" Jackson.

He was arrested during the Sharpsburg Campaign, while in the Baltimore area visiting family. He spent five months in prison.

He participated in the Battle of Brandy Station and was sighted in the after action reports of General Fitzhugh Lee and General J.E.B. Stuart for his conduct in this engagement.

On May 27, 1863, he was promoted to the rank of Major and asked to raise an independent battalion of cavalry. Before he could complete this assignment, the Gettysburg campaign interceded. During the battle, Major Gilmor was assigned command of the First and Second Maryland Cavalry, under General George Steuart's infantry brigade. Major Gilmor was the Provost Marshal of the town of Gettysburg while it was occupied.

Gilmor had organized six companies of partisan rangers by September of 1863. His command's area of operation was the Shenandoah Valley and parts of "West" Virginia. General J.E.B. Stuart ordered Gilmor to attack the Baltimore & Ohio Railroad in February of 1864.

After the defeat of Major General Lew Wallace at Monocacy on July 9, 1864, Gilmor's command acted as the spearhead for the raid around Baltimore in 1864 with General Bradley T. Johnson's infantry command.

While assigned to scout duty under General Jubal Early, Colonel Gilmor single-handedly captured a company of Federal infantry. Gilmor and Holmes Conrad, a man under his command, later captured more than 50 troopers from the First New Jersey Cavalry.

Colonel Gilmor was ordered by General Early to take his command to Hardy County, West Virginia. He was to combine with other partisans in the area and attack the Baltimore & Ohio Railroad. Colonel Gilmor was finally captured in Hardy County, on February 4, 1865. He remained a prisoner at Fort Warren until July 24, 1865.

For several years after the war, Harry Gilmor lived in New Orleans, where he married Miss Mentoria Strong. Upon his return to Maryland, he was elected colonel of cavalry in the Maryland National Guard. He also served as Baltimore City Police Commissioner from 1874 to 1879. He was a member of the Society of the Army and Navy of the Confederate States in Maryland and it's Vice-President in 1882.

Harry Gilmor died in Baltimore on March 4, 1883 at the age of forty-five. He was interred on "Confederate Hill" in Loudon Park Cemetery. To this day, people gather at his graveside on the anniversary of his birth to honor his life long service to his country.