 Henry of Grosmont , 1st Duke of Lancaster , 4th Earl of Leicester and Lancaster , KG ( c . <unk> – 23 March <unk> ) , also Earl of Derby , was a member of the English nobility in the 14th century , and a prominent English diplomat , politician , and soldier . The son and heir of Henry , 3rd Earl of Lancaster , and Maud <unk> , he became one of Edward III 's most trusted captains in the early phases of the Hundred Years ' War and distinguished himself with victory in the Battle of <unk> . He was a founding member and the second Knight of the Order of the Garter in <unk> , and in 1351 was created duke . Grosmont was also the author of the book <unk> de <unk> 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 of the <unk> of the town in <unk> . 
