The Nevilles were one of the most powerful families in England during the Wars of the Roses - the ongoing feud between the houses of York and Lancaster. Richard was knighted in 1445 and became the 16th Earl of Warwick. Married to Anne de Beauchamp, they had two daughters - Isabella and Anne. Anne would later marry Richard III.
Richard Neville, who I will call Warwick for the rest of this post, was known as a traitor and rebel during his life, and he was not trusted by King Edward IV. Like many people in England, Warwick was not supportive of the King's marriage to Elizabeth Woodville, and in 1469 he was heading a rebellion against the Crown. In July of that year, Warwick was actually successful in capturing Edward, but he did not have enough Parliamentary support behind him, so he was forced to release the King from Prison... and then he fled to France!
There, he made yet another attempt to oust Edward from the throne. He made nice with his one-time enemy, Margaret of Anjou, and with the help of the French King Louis XI, they attempted to restore Henry VI (Margaret's husband) to the throne of England. In 1470, Henry VI was released from prison and reclaimed his title, but this didn't last long. The Yorkists (aka the side the Nevilles had previously been on) fought to regain their rightful King Edward IV, and the Battle of Barnet ensued against the Lancastrians (the Neville's new side). One major factor in the weakening of Warwick's position, was the betrayal of his son-in-law, and the brother of Edward VI, the Duke of Clarence. Though Clarence had previously moved to the Lancastrian side with Warwick, thinking it would be to his advantage, he turned the tables at the last moment, deciding to fight for the Yorkists instead. Without the reinforcement of French troops that Margaret of Anjou was supposed to bring with her (but was unable to due to bad weather), and with the betrayal of Clarence, Warwick was in a bad position when Edward IV's troops met his on 14 April 1471.
Warwick's body, as well as the body of his brother, was displayed at St. Paul's Cathedral to quell rumors of his survival. After their display, they were handed over to the Neville's to be buried in the family vault in Berkshire.
One month later, Edward IV's army would also defeat and kill Margaret of Anjou's son, Prince Edward, and soon after that, Henry VI would die in the Tower of London. After these three deaths, Edward IV would be safe and free to reign England with his wife Elizabeth Woodville, until his death in 1483.
Poor, misguided Richard Neville is not so different from many Tudor men we see later. He was ambitious (to say the least), arrogant to think that he could control the monarch of England, and clearly a risk taker. He was nicknamed "the Kingmaker" for his desire and effort to control and create Kings of England - no matter how unsuccessful he was. I wonder how he would have felt if he had lived long enough to see his daughter Anne become Queen of England. Maybe the efforts he had made before wouldn't have been worth it after all! They certainly didn't do him or his family any good.
Nevertheless, a sad day for the Neville family, but a good day for Edward IV and the Yorkists! Rest in Peace, Richard Neville.