In 1448, during the renewal of the war with Scotland, Northumberland took his forces through Salisbury's West March – a grave breach of etiquette. Northumberland was defeated at the Battle of Sark, and his son Henry Percy, Lord Poynings was captured. The fact that Salisbury lost 2,000 horses trying to respond to this attack, and was then excluded (along with Northumberland) from the subsequent peace negotiations, can only have inflamed relations between the two families. Over time, the ill will might have receded, but Northumberland's second son, Thomas Percy, Lord Egremont, spent the next few years stirring up trouble in Yorkshire – particularly at York, situated between the Percy estates of Spofforth and Healaugh, and Neville's castle at Sheriff Hutton.