Relations between Charles and John II deteriorated afresh and John invaded Charles's territories in Normandy in late 1354 while Charles intrigued with Edward III's emissary, Henry of Grosmont, 1st Duke of Lancaster at the fruitless peace negotiations between England and France held at Avignon in the winter of 1354–55. Once again Charles changed sides: the threat of a renewed English invasion forced John II to make a new agreement of reconciliation with him, sealed by the Treaty of Valognes on 10 September 1355.