Angevin Empire - Sea Route
Following the fall of Normandy the Angevin (AngloNorman) Empire was made up of two widely separated parts; Gascony and England with a long sea voyage separating them.
Jersey 1204 "The value of the islands now lay in their role as a link between the distant northern and southern parts of the reconstituted Plantagenet empire - England and Gascony. The Islands had been involved in sea travel and commerce between these regions before 1204, and increasingly since. This became their primary role, from the point of view of the Plantagenet regime, probably before 1259"
(An argument based in part on the fact that royal appointed lords to the Islands were frequently heavily involved in Gascony or in other posts for the defence of the Channel)
NAM Rodger however does not mention the islands in this context but concentrates on Brest "..with the limited ability of medieval ships to navigate out of sight of land or beat to windward, a fair wind westerly down the Channel was unlikely to serve for a south-easterly course towards Bordeaux, nor visa versa. This meant that large fleets of ships often lay for long periods off Le Conquet in the 'Trade' (the english name for the northern channel out of Brest Roads), or under St Matthews Point, waiting for a fair wind. This was an obvious point to intercept ships and a frequent scene of naval battles."