The battle of Stamford Bridge (31 October or 1 November 1454) was a clash between the Neville and Percy families fought in the year before the outbreak of the Wars of the Roses, and a sign of the increasing instability brought on by the mental illness of Henry VI.
The rivalry between the Neville and Percy families dated back to the fourteenth century, when they became serious rivals for power in the north of England. It was further complicated by the forfeiture of Henry Percy, first earl of Northumberland after a revolt against Henry IV and the restoration of his grandson, another Henry Percy, second earl of Northumberland. The two families owned estates in the same parts of the country, and their holdings were closely mingled across Yorkshire and Cumberland.
To make things worse not all of the original Percy estates had been recovered, and in 1453 Sir Thomas Neville, son of Richard Neville, earl of Salisbury, had married Maud Stanhope, Lady Willoughby, an heiress who was likely to inherit two former Percy manors. This angered Thomas Percy, Lord Egremont, the second son of the earl of Northumberland, and on 24 August 1453 he attempted to block the path of the wedding part at Heworth, on the edge of York.
Although the Neville party managed to fight its way through Egremont's force, Egremont's men then attacked Neville estates across the north. Salisbury attempted to get the court to intervene, but Henry VI had just suffered the first breakdown in his mental health, and his chief advisor at the time, Edmund Beaufort, duke of Somerset, was unwilling to get involved. This pushed Salisbury into the camp of Richard, duke of York, the senior member of the English aristocracy and increasingly an opposition figure.
Events in the north were overshadowed by events in France and at court. On 17 July 1453 the English suffered a crushing defeat at Castillon. John Talbot, earl of Shrewsbury was killed and the English position in Gascony collapsed for the final time. The Hundred Years War was effectively over, and the only remaining English foothold in France was Calais. In August this news reached the court and Henry VI suffered a breakdown, becoming completely immobile and unable to communicate.
This would last for eighteen months, until his sudden recovery at Christmas 1454, and it left the court party highly vulnerable. Richard, duke of York, as the most senior nobleman and heir presumptive until the birth of Henry's son Edward on 13 October 1453. At first the court party, led by Henry's wife Margaret of Anjou, managed to keep York away from power but eventually were unable to deny him his rightful position and on 27 March 1454 he became protector of the realm.
One of his first problems was the Neville-Percy conflict. York had already come to an agreement with the Nevilles to support them in return for their support in the council, but the attack at Heworth had put the Percies in a vulnerable position anyway. They in turn realised that York could turn the full power of the government against them, and began to look for allies of their own.
They found an ally in Henry Holland, duke of Exeter. He wanted to be protector, and based his claim on his being more closely related to the king than York. Exeter and Holland had agreed an alliance early in 1454, and on 14 May they seized York. This was the high-point of their short-lived revolt. York reacted quickly and led a small army to York. Egremont and Exeter fled from the city after only five days. York had to wait until June before he felt strong enough to begin to restore order, but his mere presence in the north had spooked Exeter. The would-be protector fled to London and attempted to seek sanctuary in Westminster Abbey. York followed him south and removed him from sanctuary. He was then imprisoned in Pontefract.
This still left Egremont at large. York moved back north in an attempt to catch him, but that achievement eventually went to the Nevilles.
Despite having lost his ally, Egremont was still confident enough to raid Neville estates close to York. At the end of October (either 31 October or 1 November) Egremont and his band attacked the Neville manor of Stamford Bridge. Egremont was accompanied by his brother Richard Percy and at least 200 retainers, including a large group led by Peter Lound, bailiff of Pocklington.
The raiding party was intercepted by a Neville army led by the brothers Thomas Neville and John Neville (sons of Richard Neville, earl of Salisbury). The resulting battle was short. Lound's contingent fled from the scene early in the fighting, leaving Egremont dangerously exposed. Egremont and his brother were both captured, and were taken to the Neville stronghold at Middleham Castle.
Egremont's fate after this defeat makes it clear that the normal peacetime rules were still in place. If he had been captured after the start of the proper fighting in the following year then he would almost certainly have been killed. Instead he was placed on trial and found liable for £11,200 of damages. Egremont's annual income was only £100, and so he was taken to Newgate Prison, where he and his brother remained until they escaped on 13 November 1456.
By December 1454 Richard of York appeared to be in a very strong position. His main political enemy, Edmund Beaufort, duke of Somerset, was in the Tower of London where he faced charges related to the end of the Hundred Years War. Egremont was in debtor's prison. York's allies held the main posts in the government.
Everything changed at Christmas when Henry VI recovered his senses. York was no longer Protector and his allies lost their power. Somerset was released. Henry Percy, second earl of Northumberland decided to take a more active part in politics and support Henry VI. York and his Neville allies Salisbury and Warwick left London before their enemies could move against them, and the stage was set for the outbreak of thirty years of civil war. The first battle of the Wars of the Roses, at St. Albans, was fought on 22 May 1455, and a new and more bloodthirsty period of English politics began.