Sam Willis tells the story of the English ruler who left the most indelible mark on the castle - the great Plantagenet king, Edward I, who turned it into an instrument of colonisation. Edward spent vast sums to subdue Wales with a ring of iron comprised of some of the most fearsome fortresses ever built. Castles like Caernarfon and Beaumaris were used to impose England's will on the Welsh. But when Edward turned his attention to Scotland, laying siege to castles with great catapults, things didn't go so well for him. Show less