Henry IV settled many scores with Richard’s supporters when he took the throne. Thomas le Despenser, 1st Earl of Gloucester, was attainted for murdering his uncle Thomas of Woodstock, 1st Duke of Gloucester, in Calais (even though Henry had been a chief suspect). Edward of Norwich was sacked as the Constable of the Tower, deprived of the Dukedom of Aumale and imprisoned at Windsor Castle. Richard II’s half-brother John Holland, 1st Duke of Exeter, was also reduced to Earl of Huntingdon.
Those who had been demoted planned to assassinate King Henry and his sons so they could restore Richard to the throne. They were joined by John Montacute, 3rd Earl of Salisbury, and Exeter’s nephew Thomas Holland, 1st Duke of Surrey. The attack was due to be made during the Epiphany celebrations in January 1400 but Edward of Norwich betrayed the plot and the conspirators scattered. Montacute was caught and executed by a mob in Cirencester and Despenser met the same fate in Bristol. Thomas FitzAlan, Earl of Arundel and Surrey, tortured Richard’s half-brother John Holland, because he had treated him cruelly as a child, before the two Hollands were executed.
Owain Glyndŵr rebelled along the Welsh border in March 1402. The two Henry Percys, 1st Earl of Northumberland and Hotspur, defended the North March while Richard of Conisburgh, 3rd Earl of Cambridge, protected Herefordshire. But Owain captured Edmund de Mortimer at the battle of Bryn Glas on 22 June 1402 and Henry accused him of desertion, refused to ransom him, and confiscated his properties. So Edmund married Owain’s daughter and declared his imprisoned nephew Edmund de Mortimer, 5th Earl of March, rightful heir to the throne.
Henry Percy was also Warden of the Scottish East March and he and his son Henry Hotspur defeated the Scots at the battle of Homildon Hill on 14 September 1402, with Edmund de Mortimer’s help. Although Henry appreciated the victory, he failed to pay the Percys and made them hand over their prisoners rather than let them claim their ransom money. A furious Henry Percy denounced Henry’s ‘tyrannical government’.
The following summer, Henry Percy the younger and his uncle Thomas Percy, Earl of Worcester, joined forces with Glyndŵr and Mortimer. The king’s army engaged the Percys at Shrewsbury on 21 July 1403 and Percy’s army fled after Henry was killed. Thomas was captured and beheaded in Shrewsbury; his head was displayed on London Bridge. Even Henry Percy’s corpse was exhumed and displayed in Shrewsbury’s market place to prove he was dead. His head was then impaled on Micklegate, a gateway into York, while his body was quartered and the pieces sent to the four corners of the kingdom.
Henry IV ordered Percy’s old enemy Earl Marshal Ralph Neville, 1st Earl of Westmorland, to engage the rebels and he drove them back to Warkworth Castle. As a temporary measure, the king secured the Scottish border by appointing Neville Warden of the West March while his teenage son John of Lancaster, 1st Duke of Bedford, was made Warden of the East March. Richard Neville, 5th Earl of Salisbury, arrested Henry Percy, 1st Earl of Northumberland, for treason and he then took command of both the Scottish Marches. Hotspur’s son, another Henry Percy, was imprisoned for supporting the rebellion.
Meanwhile, Thomas FitzAlan, Earl of Arundel and Surrey, had been appointed to coordinate operations in all the Welsh Marches. He allied with the king’s half-brothers the Beauforts before defeating Glyndŵr in North Wales while Edward of Norwich, 2nd Duke of York, campaigned in South Wales. The Welsh were finally defeated by Richard de Beauchamp, 13th Earl of Warwick, at the battle of Mynydd Cwmdu in the summer of 1404.
Henry pardoned Henry Percy, 2nd Earl of Northumberland, in June 1404 but only after he had handed over his grandson. The hostage situation made no difference because Percy contacted Edmund de Mortimer and Owain Glyndŵr and they decided they would divide the conquered kingdom into three in February 1405. Glyndŵr would take the west, Percy the north and Mortimer the south.
At the same time the heirs to the throne, Edmund and Roger de Mortimer, were abducted from Windsor Castle and were being taken to their uncle when they were recaptured near Cheltenham. Constance of York was arrested and accused of helping them to escape but she blamed her brother Edward of Norwich, 2nd Duke of York, and he was imprisoned in Pevensey Castle. Edmund and Roger would be kept in prison for the rest of Henry IV’s reign.
Henry Percy, 2nd Earl of Northumberland, was furious that a Neville now held both the West and East Warden of the Scottish Marches. So he rebelled again with the Archbishop of York, Richard le Scrope, and Thomas de Mowbray, Earl of Norfolk and Nottingham. Percy attacked Witton Castle, near Durham, in May 1405 only to discover that Ralph Neville, 1st Earl of Westmorland, had already fled. Neville defeated Percy’s allies at Topcliffe in Yorkshire before marching towards York with Henry IV’s son John of Lancaster.
They encountered the rebels on Shipton Moor near York, where an outnumbered Neville convinced the rebels that their demands would be accepted and their safety guaranteed. So they disbanded on 29 May and Neville took them to the king at Pontefract Castle. Henry disregarded Neville’s promise and the rebel leaders were condemned to death. Archbishop Thomas Arundel objected to the execution of a fellow archbishop, but Richard le Scrope, Thomas de Mowbray and William Plumpton were beheaded in York on 8 June 1405.
Meanwhile, Henry Percy had fled to Scotland and the king instructed Neville to seize his castles. Percy continued plotting and he returned to England in 1408 only to be killed at the battle of Bramham Moor in Yorkshire on 19 February. His head was later displayed on London Bridge.
Richard II had supported John the Good, illegitimate son of Peter the Cruel of Portugal, in his struggle with Castile in 1385. Henry wanted to do the same and he secured the alliance with a double marriage in November 1405. His sister Philippa of Lancaster was married to King John I, and Thomas FitzAlan, Earl of Arundel and Surrey, was married to John’s illegitimate daughter Beatrice.