Image Collection 288 Items Robert Erskine-Simeon DeWitt maps, 1778-1783 This series of field sketches and finished maps of projected battle sites in New York, New Jersey, Connecticut and Pennsylvania during the Revolutionary war was begun by Robert Erskine, geographer and surveyor-general to the Continental Army, and completed by his successor, Simeon De Witt. Robert Erskine (1735-1780) was appointed Geographer to Washington's army in 1777. He surveyed both sides of the Hudson River and a large area covering the adjoining states. Many of the maps are rough field sketches, from which more detailed maps were later drawn. View Collection