The arbitrary and untrammeled rule of Richard II has alienated nearly all the English magnates.

The king is still childless: after the battle death of the Earl of March in 1398, his seven-year-old son Edmund Mortimer becomes the heir to the throne.

However, Richard is more concerned with his first cousin and childhood playmate Henry Bolingbroke, John of Gaunt's son and heir, who in 1387 had participated in the Lords Appellant's rebellion against the King.

After regaining power, Richard had not punished Henry but instead elevated him from Earl of Derby to Duke of Hereford.

However, the relationship between Bolingbroke and the King in 1398 encounters a second crisis.

Following Bolingbroke’s quarrel with Norfolk, which apparently was due to mutual suspicions stemming from their roles in the conspiracy against the Duke of Gloucester, a parliamentary committee decides that the two should settle the matter by battle.

The King calls a duel of honor at Gosford Green near Coventry.

Before the duel can take place, however, Richard banishes Henry from the kingdom (with the approval of Henry's father, John of Gaunt) for ten years to avoid further bloodshed between Bolingbroke and Norfolk, who is exiled for life.

Roger de Mortimer, 4th Earl of March and 6th Earl of Ulster (grandson of Lionel of Antwerp, 1st Duke of Clarence), had in 1385 been publicly acknowledged as heir presumptive to the English crown.

He had accompanied Richard II to Ireland in 1394 but, notwithstanding a commission from the king as lieutenant of the districts over which he exercised nominal authority by hereditary right, he had made little headway against the native Irish chieftains.

The following year Mortimer had nevertheless, been given broader authority as lieutenant of Ireland.

March enjoys great popularity in England though he has taken no active part in opposing the despotic measures of the King.

He is killed on July 20, 1398, at the Battle of Kells, a border town of the Pale, in a fight with an Irish clan, and is buried in Wigmore Abbey in Hereford, his titles and the designation of heir presumptive passing to his young son, Edmund Mortimer, 5th Earl of March.

Percy and his son, Henry Percy, known as "Hotspur", have been given the task of subduing the rebellion of Owain Glydwyr but their attempts to make peace with the Welsh rebels have not meet with the king's approval.

After King Henry IV improperly and illegally claims the captured Earl of Douglas and the right to ransom in 1403, the angered Percys turn against Henry in favor of Edmund de Mortimer, 5th Earl of March, who has a rightful claim to the English throne, and conspire with Glyndwyr.

A dispute between the cunning and powerful Welsh lord Owen Glendower and an English neighbor in 1400 had sparked Glendower’s ruthless revolt against Henry IV, whom he had earlier supported.

Aided by countrywide resentment of high taxes and poor administration imposed by the English, Glendower, proclaimed prince of Wales in 1400, had rapidly ousted Henry’s forces from castles and towns in Wales.

Glendower in 1402 had gained the support of Edmund de Mortimer.

The powerful English Percys, after quarreling with Henry over the ransom of Scottish prisoners in 1402, had turned against him, becoming supporters of Glendower in his Wales-based rebellion.

With the defeat of the Percys at Shresbury in 1403, Glendower had turned to France for aid.

After seizing the key castles of Aberystwyth and Harlech by 1404, the able Glendower had gained control of most of Wales and the recognition of King Charles VI of France, with whom he has made an alliance.

Glendower begins losing battles in 1405, however, and, because the promised French support fails to appear, will continue to do so.

Northumberland, pardoned by his peers, has by 1405 involved himself in a new conspiracy to dethrone Henry, whom he has never forgiven for Shrewsbury, and crown Edmund de Mortimer.

The king is alerted to the plot, however, and has Northumberland’s co-conspirators, the Earl of Nottingham and Richard Le Scrope, the Archbishop of York, beheaded.

Northumberland escapes to Scotland.

Henry V, on his ascension of the English throne in April 1413, restores the Percy family’s lands and titles and gives the remains of Richard II an honorable reburial.

The new king releases the imprisoned Edmund de Mortimer.

Richard of Conisburgh, a grandson of Edward III (through his fifth son Edmund, Duke of York and husband of Anne Mortimer, had in the Parliament of 1414 been created Earl of Cambridge, a title formerly held by his elder brother, Edward, 2nd Duke of York, who had earlier ceased to be Earl of Cambridge either by resignation of the title, or deprivation.

However Richard's creation as Earl of Cambridge had brought with it no accompanying grant of lands, and according to Harriss, Cambridge was 'the poorest of the earls' who were to set out on Henry V's invasion of France, and lacked the resources to properly equip himself for the expedition. (Harriss, G. L. (2004). Richard, earl of Cambridge (1385–1415). Oxford Dictionary of National Biography)

Perhaps partly for this reason, Cambridge conspires with Henry Scrope, 3rd Baron Scrope of Masham (whose uncle Richard le Scrope had been executed for his part in a 1405 revolt also supporting Mortimer's right), and Sir Thomas Grey (whose son, Thomas, had been betrothed in 1412 to Cambridge's only daughter, Isabel) to depose King Henry, and place his late wife Anne's brother, Edmund Mortimer, 5th Earl of March, on the throne.

The nominal principal, the Earl of March, had informed King Henry of the plot on July 31, stating that he had only just become aware of it.

Richard, Scrope, and Grey are promptly arrested.

The trial takes place in Southampton, on the site now occupied by the Red Lion Inn.

Mortimer is on the commission that condemns Cambridge to death.

Grey is beheaded on August 2 and the two peers on August 5, both in front of the Bargate, and buried in the chapel of God's House at Southampton.

Henry, satisfied, on August 11 sails for France.

The heirs of those who had suffered in the last reign are restored gradually to their titles and estates.

On the other hand, where Henry sees a grave domestic danger, he acts firmly and ruthlessly—such as the Lollard discontent in January 1414, including the execution by burning of Henry's old friend Sir John Oldcastle, so as to "nip the movement in the bud" and make his own position as ruler secure.

The last Mortimer dies in 1425, and Richard, duke of York, the fourteen-year-old son of Anne Mortimer and the executed Richard, earl of Cambridge, inherits that family's claim to the throne, which is based on descent from Lionel, duke of Clarence, the third son of English king Edward III.