Roger Mortimer: The Greatest Traitor Who Ruled as King

Written by Simon Williams

The Marcher Lord in Waiting

Consider the sheer audacity of it. A Marcher baron, born in 1287 at Wigmore Castle amid the wild borders of Wales and England, rises to become the de facto sovereign of the realm. Roger Mortimer, third Baron Mortimer of Wigmore, later first Earl of March, was no mere adventurer. He was a man of ancient blood, great-great-grandson of William Marshal, that legendary regent who saved England from chaos, and heir to vast estates straddling the Welsh Marches and Ireland through his shrewd marriage to Joan de Geneville, a wealthy heiress. At seventeen, upon his father's death in 1304, he inherited power that few could match in the turbulent reign of Edward II.

Mortimer began loyally enough. He served the king faithfully: constable of Wallingford, lieutenant in Ireland, a soldier who crushed rebellions and held the frontiers. Yet loyalty in Plantagenet England was a fragile thing, easily shattered by royal favouritism. Edward's obsession with Piers Gaveston, then Hugh Despenser the Younger, alienated the great lords. Mortimer, proud and ambitious, joined the baronial opposition. In 1321–22, he rebelled openly against the Despensers' rapacity. Captured, he was sentenced to death, commuted to life imprisonment in the Tower. There, in a daring escape in 1323, scaling walls, vanishing into the night, he fled to France. A condemned traitor, yet far from finished.

The Alliance with the Queen

Exile in Paris proved the making of him. Queen Isabella of France, sent in 1325 to negotiate over Aquitaine, refused to return to her husband. Edward's regime had humiliated her: lands seized, influence stripped, the Despensers lording it over all. In the French court, Isabella met Mortimer again. What began as political convenience, two exiles united against a common foe, blossomed into something more intimate. Chroniclers whispered of adultery; modern historians debate passion versus pragmatism. Either way, they forged a formidable partnership. Mortimer supplied military nous and baronial support; Isabella brought royal legitimacy and French backing.

In September 1326, they invaded. A small force landed near Ipswich. Edward's support evaporated. Nobles defected wholesale; the Despensers were hunted down. Hugh the Younger suffered a barbaric execution at Hereford, drawn, hanged, quartered, entrails burned. Edward himself was taken in Wales, deposed by Parliament in January 1327, the first such act since the Conquest. The king abdicated in favour of his fourteen-year-old son, Edward III. Mortimer and Isabella assumed regency. For three years, Mortimer ruled England in all but name.

The King Without a Crown

Power corrupts, and absolute power corrupts absolutely, even when worn with borrowed robes. Mortimer gorged himself. Created Earl of March in 1328, he amassed titles, lands, offices. He negotiated the Treaty of Northampton with Scotland, Bruce recognised, English claims abandoned, seen by many as shameful surrender. He strutted at court, rewarded cronies, alienated the young king. Rumours swirled: he had orchestrated Edward II's murder at Berkeley Castle in 1327, the infamous red-hot poker tale (likely later invention, yet the stink of regicide clung). Whether murderer or not, Mortimer had removed a king and installed another under his thumb.

His arrogance knew no bounds. He behaved as king: summoning parliaments, dispensing justice, even styling himself protector of the realm. The nobility seethed; the young Edward III, coming of age, watched and waited. In October 1330, the coup came at Nottingham Castle. Edward's men seized Mortimer in Isabella's chambers, dramatic proof of their closeness. Tried for treason, assuming royal power, procuring the old king's death, enriching himself at the crown's expense, he was condemned without proper defence. On 29 November 1330, at Tyburn, he was hanged like a common felon, his vast estates forfeited. Aged forty-three, the man who had ruled England died ignominiously.

Legacy: Traitor, Tyrant, or Tragic Overreacher?

Mortimer's fall was swift and total. His name became synonym for overweening ambition: the favourite who supplanted the king, the lover who cuckolded him, the regent who forgot his place. Chroniclers vilified him as traitor supreme; later writers echoed the charge. Yet peel away the propaganda. Here was a man of genuine ability, literate, strategic, respected in his early career. He had endured imprisonment, engineered a remarkable escape, led a successful invasion, stabilised a fractured realm after deposition. Without him, Edward III's minority might have collapsed into anarchy.

His greatest sin? Hubris. He forgot the fragility of power borrowed from a boy-king. Edward III, once freed, restored royal authority with vigour, launching the Hundred Years' War, founding the Order of the Garter. Mortimer's son Edmund suffered forfeiture, but the family recovered: grandson Roger became second Earl of March, a Garter knight, rebuilding prestige.

In the end, Roger Mortimer stands as a cautionary tale of medieval politics. A loyal servant turned rebel, a prisoner turned regent, a ruler who reached too far and paid the ultimate price. He bent England to his will for three intoxicating years, then was broken by the very monarchy he had preserved. Not the greatest traitor in cold blood, perhaps, but the most spectacular overreacher. In the annals of English history, few men grasped the crown so boldly, or fell so completely.

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