McCarthy, in the meanwhile, had cooled down and was inclined to turn aside this new challenge in a humorous vein. He suggested to Mason's seconds that the antagonists jump from the dome of the capitol; but the matter had gone too far for joking and he was told his suggestion did not comply with the code. Again and yet again he offered similar absurd solutions and being rebuffed and in an effort to frighten Mason, suggested shotguns loaded with buckshot at ten paces, suicidal terms which were modified by the seconds to charging the weapons with a single ball and the distance to twelve feet.
After the fatal outcome of the Hamilton-Burr duel in 1804, a wave of hostility to the whole institution of duelling had swept the country. In January, 1810, Virginia had passed an act making the death of a duellist within three months of the encounter, murder, and providing that the survivor should be hung. Moreover, it was provided that the mere act of sending or accepting a challenge should make the offender incapable of holding public office. Therefore it was expedient that the meeting should not be held in Virginia and a field, along the side of which ran a little brook, near Bladensburg in Maryland, was selected for the affair. Principals, seconds and referee arrived at a nearby inn on the night of the 5th February, 1819, and at 8:00 o'clock the next morning, in the bitter cold and snow, the cousins confronted each other on the field, standing so close to one another that their "barrels almost touched." As the signal was given both fired and then fell to the ground--Mason dying and McCarthy dangerously wounded. Mason's body was brought back to Leesburg where it rested for a while in the old stone house on Loudoun Street now owned by Mr. T. M. Fendall, before burial in the St. James graveyard in Church Street with religious and Masonic rites. There the grave is still to be seen. It is said that Mrs. Mason locked the main entrance of Selma after the funeral and that no one again used it until her only son came of age--a son destined to meet his death, many years later, as an American officer, in the battle of Cerro Gordo in our war with Mexico. Tradition has it that ever after the duel, McCarthy was a morose and haunted man. A gruesome detail is added that long after his death his marble gravestone was removed to the Purcell drug store in Leesburg and there used for many years as a slab on which prescriptions were compounded.