The Mortimers already held lands in Ireland through the marriage of  Roger’s grandfather to the heiress Maud de Braose. By his own marriage Roger became one of the principal lords in Ireland and much of his early career was concerned with Irish affairs. As far as we know, he was the first lord of Wigmore to actually set foot in Ireland, which he visited first in 1308.

Roger was very close to his uncle, the warlike Roger Mortimer of Chirk, and in 1314 both of them were with Edward II on the Scottish campaign which resulted in the ignoble defeat at Bannockburn. The younger Roger was captured, but released by the Scottish king, Robert the Bruce, who tasked him with returning king Edward’s privy seal and royal shield to him.

Edward II’s humiliation at Bannockburn had been unexpected and traumatic for the English. Buoyed by his great victory, Robert the Bruce saw an opportunity to increase his authority in the region and put further pressure on the English king. English rule in Ireland was widely resented by the native Irish and Robert chose this moment of low English morale to offer the Irish a new deal, in alliance with Scotland. He sent over an army led by his brother Edward Bruce. Roger Mortimer rushed back to Ireland to defend his lands but was defeated at the battle of Kells in 1315. Though Dublin and a handful of castles, including Trim, held out against Edward Bruce, he was crowned King of Ireland on May 1st 1316.

By 1320 Roger Mortimer had come a very long way in a fairly short time. Now very rich, he had demonstrated his ability as a strong and effective leader and negotiator and his loyal service ensured that he was trusted by the king. The future must have looked very bright indeed for Roger, but there was one fly in the ointment that was going to turn his world upside-down and that fly was Hugh Despenser the Younger.

Despenser was cunning, ambitious and utterly ruthless. Having skilfully managed to secure a pre-eminent place at court as the king’s favourite, he exploited every opportunity for personal advancement at the expense of others and he particularly singled out Roger Mortimer. Roger was clearly a rival, but there was a deeper reason for Despenser’s hatred. At the battle of Evesham back in 1265, Roger’s grandfather had slain Hugh Despenser’s grandfather and this had not been forgiven. Despenser vowed to destroy Mortimer –  and he almost succeeded.

As the younger Despenser’s influence grew he became more and more autocratic and high-handed. The turning point arrived when, with the acquiescence of the king, he began to acquire lands in south Wales that actually belonged to other people. In this situation, all the Marcher lords felt threatened, but they were in a very difficult position. Basically loyal by nature, any move against Despenser would effectively be an act of rebellion against the king. Between a rock and a hard place they reluctantly moved into active opposition. When Roger finally joined the other barons he was quickly stripped of his title as Justiciar of Ireland. His uncle, Roger of Chirk, also joined the rebels after 50 years of loyal service to the crown.

Roger and Isabella planned an invasion of England and a fleet was assembled with the help of Count William of Hainault. Before the final decision was taken, both sides made demands: Isabella insisted that Despenser should be exiled; Edward urged his son to leave Isabella and return to England; but nothing happened. Just before sailing, Roger heard that his old uncle, Roger Mortimer of Chirk had died in the Tower, while in the custody of Hugh Despenser. Failure to remove Despenser was to cost Edward his crown and maybe his life. On 24th September 1326, Roger and Isabella landed in Suffolk with possibly as few as 1100 men.

Edward didn’t see this small force of foreigners as much of a threat. He summoned the huge total of 47,640 men to take up arms immediately and offered a reward of £1,000 for Roger’s head. But Roger and Isabella played their cards well. Though Roger was the military commander, Isabella now took the lead and she presented herself as a religious and deeply-wronged queen coming with her son, the heir to the throne, to rid the country of the pernicious Despenser. It was the right approach and the numbers going to her aid grew rapidly. Edward’s great army failed to materialise and his support quickly evaporated. By late October the king was on the run with Hugh Despenser and a few retainers.

There remained the difficult question of what to do about Edward II. While he lived, he would always be a focal point for rebellion, but to be seen to execute an anointed king would be equally hazardous. The first step was to officially depose him and Roger skilfully managed the legal process to achieve this. On 20th January 1327 Edward was led into the great hall of Kenilworth castle where he was imprisoned. After his crimes had been read out, he offered to abdicate in favour of his son. It is not known precisely what happened to Edward II after his abdication. He was transferred to Berkeley Castle and, not surprisingly, attempts were soon made to free him. Then on 21st September 1327 it was announced that he had died of natural causes and his funeral was held in Gloucester cathedral on 20th December. However, it was widely believed that Edward II had actually been murdered and Roger was the obvious suspect. Be that as it may, there is absolutely no evidence to support the popular story that Edward had a red-hot ‘poker’ shoved into his anus to avoid any external indication of murder, or possibly as a crude reference to his supposed homosexuality. This gory tale emerged much later.

But did Edward actually die at all in 1327? There is circumstantial evidence that he was moved from Berkeley to Corfe castle and that he then survived in secret exile on the Continent for a further 15 years. But why would Roger possibly prefer Edward to survive? While recognising the political necessity for him to be officially dead, neither Roger nor Isabella would have wanted the king’s blood on their hands. Isabella was a devout Christian and, after all, Edward was her husband. And Roger knew that he was only alive because Edward commuted the death sentence passed on him in 1322. All along their real enemy was Despenser, not the king.

All this time, of course, Roger was married to Joan de Geneville. When Roger had been sent to the Tower in 1322, all his possessions were forfeit and his wife was imprisoned too. It was to be five years before Roger saw his wife again, during which time he had acquired a beautiful and powerful new partner. Joan seems to have accepted the situation philosophically, but it must nevertheless have been difficult for her when she was expected to entertained Isabella at Ludlow castle in 1329.

Roger had himself created Earl of March in 1328, a significant title as all previous earldoms had been of single counties. As the inevitable result of unbridled power, his arrogance increased and he began to ‘play the king’ more openly. Previously deferential towards Edward III, he now was seen to walk beside him, sit in his presence and insist that his word was obeyed rather than the king’s. He organised a great Round Table tournament at Wigmore. With his queen by his side, he had himself, rather than Edward, crowned as King Arthur, an attempt to pass himself off as a member of the royal family. His own son, Geoffrey, labelled him the ‘King of Folly’. Edward III would soon be 17. He was finding Roger’s arrogance and control increasingly irksome and looking for a way of exerting his own authority.

It has been argued that Edward III was made aware that his father was still alive soon after the king’s apparent interment at Gloucester. Certainly Edward II’s brother, the earl of Kent, believed it and Roger learned that he was plotting to free the ex-king from Corfe castle. His response was as tyrannical as Despenser’s had been: Kent was to lose his life and his family were to be disinherited. Though the sentence was shockingly cruel, the king felt he had no option but to agree. When it came to the earl’s execution on 19th March 1330, they had difficulty finding anyone willing to cut off his head.