Mortimer, Edmund de, 3d earl of March and 1st earl of Ulster definition of Mortimer, Edmund de, 3d earl of March and 1st earl of Ulster in the Free Online Encyclopedia.

Mortimer, Edmund de, 3d earl of March and 1st earl of Ulster (də môr`tĭmər), 1351–81, English nobleman. He succeeded (1360) his father, Roger, 2d earl of March, married (1368) Philippa, daughter of Edward III's son Lionel, duke of Clarence, and on Lionel's death (1368) inherited his estates and the title of earl of Ulster. Later the house of York (see York, house of York, house of, royal house of England, deriving its name from the creation of Edmund of Langley, fifth son of Edward III, as duke of York in 1385. The claims to the throne of Edmund's grandson, Richard, duke of York, in opposition to Henry VI of the house of
..... Click the link for more information. ) traced part of its claim to the throne to this union. Mortimer held the office of marshal of England from 1369 to 1377 and supported the party that opposed John of Gaunt John of Gaunt [Mid. Eng. Gaunt=Ghent, his birthplace], 1340–99, duke of Lancaster; fourth son of Edward III of England. He married (1359) Blanche, heiress of Lancaster, and through her became earl (1361) and duke (1362) of Lancaster.
..... Click the link for more information. . After the accession of Richard II (1377) he was elected to the boy king's first council. In 1379 he was sent as lieutenant of Ireland to subdue Irish unrest. His daughter Elizabeth married Sir Henry Percy, known as Hotspur.