Baptized David Jackson Kemper by Dr. Benjamin Moore, the Assistant Rector of his parents' congregation at New York City's Trinity Church, he would eventually drop the given name "David." He had been born in the Hudson River Valley of New York, where his parents had taken temporary refuge during a smallpox outbreak in New York City. He was the son of Col. Daniel Kemper, a former aide-de-camp to Gen. George Washington at the battles of Germantown and Monmouth during the American Revolution, and Elizabeth (Marius) Kemper, who descended from well-known families of the Dutch New Amsterdam era.