http://en.wikipedia.org/wiki/Edmund_Mortimer,_3rd_Earl_of_March
Edmund de Mortimer, 3rd Earl of March and jure uxoris Earl of Ulster (1 February 1352 – 27 December 1381) was son of Roger Mortimer, 2nd Earl of March, by his wife Philippa, daughter of William Montacute, 1st Earl of Salisbury and Catherine Grandison.