Edmund de Mortimer, (1391—1425), 5th Earl of March and Ulster, son of the 4th earl, succeeded to his father’s claim to the crown as well as to his title and estates on the death of the latter in Ireland in 1398. In the following year Richard II of England was deposed and the crown seized by Henry of Lancaster. The young earl of March and his brother Roger were then kept in custody by Henry IV, who, however, treated them honourably, until March 1405, when they were carried off from Windsor Castle by the opponents of the Lancastrian dynasty, of whom their uncle Sir Edmund Mortimer and his brother-in-law Henry Percy (Hotspur) were leaders in league with Owen Glendower. The boys were recaptured, and in 1409 were committed to the care of the prince of Wales. On the accession of the latter as Henry V, in 1413, the earl of March was set at liberty and restored to his estates, his brother Roger having died some years previously; and he continued to enjoy the favour of the king in spite of a conspiracy in 1415 to place him on the throne, in which his brother-in-law, Richard, Earl of Cambridge, played the leading part. March accompanied Henry V throughout his wars in France, and on the king’s death in 1422 became a member of the council of regency. He died in Ireland in 1425, and as he left no issue the earldom of March in the house of Mortimer became extinct, the estates passing to the last earl’s nephew Richard, who in 1435 was officially styled duke of York, earl of March and Ulster, and baron of Wigmore. Richard’s son Edward having ascended the throne in 1461 as Edward IV, the earldom of March became merged in the crown.