Roger de Mortimer, 3rd Baron Mortimer, 1st Earl of March (25 April 1287 – 29 November 1330), was an English nobleman and powerful
Marcher lord who gained many estates in the
Welsh Marches and Ireland following his advantageous marriage to the wealthy heiress
Joan de Geneville, 2nd Baroness Geneville. In November 1316, he was appointed
Lord Lieutenant of Ireland. He was imprisoned in the
Tower of London in 1322 for having led the Marcher lords in a revolt against
King Edward II in what became known as the
Despenser War. He later escaped to France, where he was joined by Edward's
queen consort Isabella, whom he took as his mistress. After he and Isabella led a successful invasion and rebellion, Edward was subsequently deposed; Mortimer allegedly arranged his murder at
Berkeley Castle. For three years, Mortimer was
de facto ruler of England before being himself overthrown by Edward's eldest son,
Edward III. Accused of assuming royal power and other crimes, Mortimer was executed by
hanging at
Tyburn.