Edward's sea-supplied Welsh castles followed an existing pattern. The Tower of London asserted royal control over the city while remaining accessible from the Thames. Water access meant that people, building material, supplies, and a relief army could still reach the fortress if London became hostile. The same position supported maintenance, logistical security, and resupply during a siege. In Wales, coastal control could also support economic control inland, making location part of both the castle's military and political function.
Notable Point · 16:52-18:42
The Tower of London as a water-access precedent
The Tower of London shows that placing a castle beside navigable water joined political control to reliable movement, supply, maintenance, and relief.