 He later commanded the North Atlantic Squadron.Trenchard was born in Brooklyn, New York, the son of U.S. Navy Captain Edward Trenchard and Eliza Sands Trenchard, the daughter of merchant and politician Joshua Sands.He was named for the distinguished naval officer Stephen Decatur, a close friend of his father, and was a direct descendant of George Trenchard (1655–1712), from the village of Wolverton in Dorset, who had come to the United States with William Penn in 1682.