The son and heir of Henry, 3rd Earl of Lancaster, and Maud Chaworth, Grosmont became one of King Edward III's most trusted captains in the early phases of the Hundred Years' War and distinguished himself with victory in the Battle of Auberoche. He was a founding member and the second Knight of the Order of the Garter in 1348, and in 1351 was created Duke of Lancaster. An intelligent and reflective man, Grosmont taught himself to write and was the author of the book "Livre de seyntz medicines", a highly personal devotional treatise. He is remembered as one of the founders and early patrons of Corpus Christi College, Cambridge, which was established by two guilds of the town in 1352.