John Neville, 1st Marquess of Montagu KG (c.1431 – 14 April 1471) was, until his final years, a Yorkist leader in the Wars of the Roses, brother of Warwick the Kingmaker and perhaps best known for eliminating Lancastrian resistance in the north of England in the first three years of the reign of Edward IV of England.
Montagu was the third son of Richard Neville, 5th Earl of Salisbury and Alice Montacute, 5th Countess of Salisbury, and a younger brother of Richard Neville, 16th Earl of Warwick, "the Kingmaker".
He was knighted by King Henry VI at Greenwich on 5 January 1453, alongside Edmund and Jasper Tudor, his brother Thomas Neville, William Herbert, Roger Lewknor, and William Catesby. He was from the branch of the Neville family based at Middleham Castle in Yorkshire, rather than that of Westmorland. It has been claimed that he, as a 'landless younger son' caused their long-running feud with the Lancastrian Percy family of Northumberland. He was certainly involved in the confrontation between the two families and their armed retinues which took place between Heworth and Stamford Bridge on 24 August 1453, following which 'much slaughter of their followers was alleged' by both sides.
He was created Lord Montagu in 1460, alongside Lord Scales, following Richard, Duke of York's return to England. He fought with his father and brother Thomas at the Battle of Blore Heath in 1459, and was captured and imprisoned in Chester Castle by the Lancastrians, for which he was attainted. After the Yorkist victory at Northampton he was released, but was captured again at the Second Battle of St Albans in 1461.
Following his second release from imprisonment, he led the Yorkist forces in the north of England, defeating the Lancastrians at Hedgeley Moor and again at Hexham (both 1464).
In reward for driving out the Lancastrians, the new Yorkist King Edward IV invested him in 1462 as a Knight of the Garter and the following year appointed him warden of the east march. In 1464 he was also created Earl of Northumberland, a title which had long been held by the disgraced Percy family, and awarded the Percy estates confiscated after the Battle of Towton. However, when Henry Percy was rehabilitated in 1470, Montagu was forced to give up the earldom and many important offices in favour of his former foe. This was possibly due to Edward fearing troops from Northumberland would not be loyal.
He was in compensation created Marquess of Montagu, but without suitable estates or income to support such a dignity. Now set against Edward IV, he changed his allegiance and joined his brother Richard, Earl of Warwick, in the short-lived readeption of the Lancastrian King Henry VI. Montagu returned to high office in the north, but was killed with his brother Richard fighting the Yorkist forces at the Battle of Barnet in 1471.
More information on the Wikipedia page [1].