 Complete the following phrase:  De la More gravitated into the service of Richard Neville, Earl of Salisbury by 1452, and perhaps as early as the previous decade. Within a few years, Salisburys sons became engaged in a bitter feud with those of the Earl of Northumberland, led by Thomas Percy, Lord Egremont. At the same time, the King was mentally incapacitated and unable to govern. The House of Lords had appointed the Duke of York protector during the Kings illness, and York, in turn, made Salisbury his Lord Chancellor. Following the Yorkist victory at the 