As a result of his capture and imprisonment in York, Montagu escaped participation in the biggest and probably bloodiest battle of the Wars of the Roses which took place on 29 March 1461 at Towton in Yorkshire. This decisive Yorkist victory led to Montagu being released the next day, when the son of the Duke of York – and England's "de facto" new king – Edward IV entered York in triumph. Montagu and Warwick then stayed in the north to attempt the recapture of northern castles still in Lancastrian hands; as John Gillingham has put it, "the unfinished military business would have to be left to the Nevilles." And on 10 May 1461 Montagu was commissioned to raise troops against both the Lancastrian remnants and the king of Scotland. One of Montagu's first actions was to successfully raise the siege of Carlisle, "with prompt action." Carlisle had had its suburbs burnt and been under siege from June by a Scottish-Lancastrian force, but was easily relieved by him, apparently killing 6,000 Scots and Lord Clifford's brother in the process, before Warwick had even arrived.