In May 1643, a plot was uncovered organised by Edmund Waller, a leading moderate and cousin of John Hampden and William Waller, commander of the Western Association Army. The conspirators intended to take control of London, arrest Pym and other leaders of the 'War Party', then negotiate with the king. Although probably aware of the plan, Holles avoided arrest, but the revelation hardened opinion within Parliament against a peace settlement. At the same time, Royalist victories in 1643 made Charles unwilling to negotiate until the war turned against him in late 1644; Holles represented Parliament at the November 1644 to January 1645 Uxbridge negotiations, but these made little progress.