The rupture had begun in 1402 after the Battle of Homildon Hill, where English forces led by Northumberland defeated an invading Scottish army and captured a large number of Scottish nobles. By the conventions of late-medieval warfare, captured noblemen could buy their freedom through ransom, and Northumberland stood to make a fortune from the prisoners. King Henry IV, however, was in deep financial trouble - the costs of his own coup, the ongoing war against Owain Glyndwr in Wales, the unrest in parts of England and Wales still loyal to the murdered Richard II - and he demanded that the Percys hand over the Scottish prisoners for token compensation. The demand was as much about asserting royal authority over Northumberland, which the Percys ruled almost as a private fief, as it was about money. Northumberland refused. He declared his support for Edmund Mortimer, 5th Earl of March, whose claim to the throne was arguably better than Henry's own.

The first round went badly. At the Battle of Shrewsbury in July 1403 the Earl's son Henry Hotspur was killed in the fighting and Thomas Percy, Earl of Worcester - Northumberland's brother and the builder of Wressle Castle - was captured and beheaded two days later. Northumberland himself retreated to Scotland. He emerged again in 1405 in alliance with Archbishop Scrope of York; that rebellion collapsed and Scrope was executed for treason. Three years of further plotting in exile produced one last attempt. In early 1408 Northumberland gathered an army of Lowland Scots and loyal Northumbrian retainers and marched south toward York. Owain Glyndwr's Welsh rebellion, which the Percys had hoped would draw away royal forces, was already collapsing. No other rising materialised. The army was significantly smaller than the one that had gathered at Shrewsbury five years earlier.

At Bramham Moor, on the gently rising ground south of Wetherby and about 3.5 miles west of Tadcaster, the Earl's force was met by a hastily assembled defence of Yorkshire levies and noble retinues led by Sir Thomas Rokeby, the High Sheriff. The exact sizes are not recorded. The contemporary chronicles agree that the armies were small by the standards of the period. Northumberland positioned his men carefully and waited for Rokeby's arrival at around two o'clock in the afternoon. The details of the fighting itself are thin in the sources. It seems to have followed the pattern of most medieval battles between English and Scottish forces in that century: English longbowmen thinning the Scottish ranks at distance, then a charge with the main body to close the matter. The melee in the centre of the field was, by all accounts, brief and violent.

Northumberland died fighting a rearguard action as his army was routed. His ally Thomas Bardolf, 5th Baron Bardolf, was mortally wounded early in the action and died of his injuries later. Few of the Earl's soldiers escaped the pursuit back to Scotland. The Earl's body was hanged, drawn, and quartered - the traditional punishment for traitors - with his head displayed on London Bridge and other parts of his anatomy on the gates of various northern cities. Among the captured rebels executed afterwards was the Abbot of Hailes, who was wearing full armour and so could not plausibly claim non-combatant status. The Bishop of Bangor, found in his vestments, was spared. Eventually the parts of the Earl's body were reunited and given Christian burial at York Minster. The Percy Rebellion was over. The Lancastrian dynasty he had helped to power, then tried to overthrow, would rule England for another sixty-three years.