The eldest, John Watts de Peyster Jr., performed duty as an aide-de-camp and artillery commander with the Army of the Potomac and mustered out as a brevet brigadier general; Frederic de Peyster III, was a colonel and surgeon; while the youngest, Johnston de Peyster, was a second lieutenant in charge of a battery of artillery credited with hoisting the first Union flag over the Confederate capitol of Richmond, Virginia, after its fall.
The eldest, John Watts de Peyster Jr., served as an aide-de-camp and artillery commander for the Army of the Potomac and retired as a brevet brigadier general; Frederic de Peyster III was a colonel and surgeon; while the youngest, Johnston de Peyster, was a second lieutenant in charge of an artillery battery that raised the first Union flag over Richmond, Virginia, after its fall.