In 1214 John began his final campaign to reclaim Normandy from Philip. John was optimistic, as he had successfully built up alliances with the Emperor Otto, Renaud of Boulogne and Count Ferdinand of Flanders; he was enjoying papal favour; and he had successfully built up substantial funds to pay for the deployment of his experienced army. Nonetheless, when John left for Poitou in February 1214, many barons refused to provide military service; mercenary knights had to fill the gaps. John's plan was to split Philip's forces by pushing north-east from Poitou towards Paris, whilst Otto, Renaud and Ferdinand, supported by William Longespée, marched south-west from Flanders.

When did John begin his final campaign to reclaim Normandy?