Henry of Grosmont, Duke of Lancaster (– 23 March 1361) was an English statesman, diplomat, soldier, and Christian writer. The owner of Bolingbroke Castle in Lincolnshire, Grosmont was a member of the House of Plantagenet, which was ruling over England at that time. He was the wealthiest and most powerful peer of the realm. 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. Origins Henry of Grosmont was the only son of Henry, 3rd Earl of Lancaster (c. 1281–1345); who in turn was the younger brother and heir of Thomas, 2nd Earl of Lancaster (c. 1278–1322). They were sons of Edmund Crouchback, 1st Earl of Lancaster (1245–1296); the second son of King Henry III (ruled 1216–1272) and younger brother of King Edward I of England (ruled 1272–1307). Henry of Grosmont was thus a first cousin once removed of King Edward II and a second cousin of King Edward III (ruled 1327–1377). His mother was Maud de Chaworth (1282–1322). On his paternal grandmother's side, Henry of Grosmont was also the great-great-grandson of Louis VIII of France. Little is known of Grosmont's childhood and youth. Due to his uncle Thomas' increasingly hostile relations with King Edward II—culminating in his rebellion and execution in 1322—historian Kenneth Fowler suggests that this period "must have been quite eventful" and that Grosmount's "fortunes and opportunities were inextricably bound up with the tragic events of these years". The year and place of his birth are not known with certainty. He is believed to have been born in about 1310 at Grosmont Castle in Grosmont, Monmouthshire, Wales. According to his own memoirs he was a "good looking, youth. Tall fair and slim" and better at martial arts than at academic subjects; he did not learn to read