Query: Who blocked John's relief operation?
Context: John attempted a synchronised operation involving land-based and water-borne forces, considered by most historians today to have been imaginative in conception, but overly complex for forces of the period to have carried out successfully. John's relief operation was blocked by Philip's forces, and John turned back to Brittany in an attempt to draw Philip away from eastern Normandy. John successfully devastated much of Brittany, but did not deflect Philip's main thrust into the east of Normandy.