On September 22, 1864, Union forces executed six of Mosby's men who had been captured out of uniform (i.e. as spies) in Front Royal, Virginia; a seventh (captured, according to Mosby's subsequent letter to Sheridan, "by a Colonel Powell on a plundering expedition into Rappahannock") was reported by Mosby to have suffered a similar fate. William Thomas Overby was one of the men selected for execution on the hill in Front Royal. His captors offered to spare him if he would reveal Mosby's location, but he refused. According to reports at the time, his last words were, "My last moments are sweetened by the reflection that for every man you murder this day Mosby will take a tenfold vengeance." After the executions a Union soldier pinned a piece of paper to one of the bodies that read: "This shall be the fate of all Mosby's men."