During the First Barons' War he was until 1 October 1215, in the entourage of the king, who gave Neville the Governorship of Scarborough Castle on that day, receiving funds from the king to strengthen the fortifications of the castle. In the winter of 1215-1216 he defended York Castle and York against the troops of the baronial opposition. In early 1216, Neville was appointed Sheriff of Yorkshire, which he remained until 1223. Unlike many other barons, he remained a loyal supporter of the king until the death of King John in October 1216.