Fortification spending and strategic value

Harlech's estimated ten-percent share of Edward I's castle budget invites comparison with German fortification of the Channel Islands during the Second World War. The comparison assigns roughly twelve percent of the Atlantic Wall budget to each of Jersey and Guernsey, about a quarter between them. That estimate is used to question the return on such heavily defended positions: retaking the islands would not open a second front in France, and the Allies could bypass them. Harlech saw use in the rebellions of Madog ap Llywelyn and Owain Glyndwr, the Wars of the Roses and the English Civil War. Between wars, the argument for its value includes enforcing royal peace and providing a visible reminder of state power.