The close geography makes submarines dangerous to both sides rather than offering Germany a one-sided answer to British strength. German boats can attack the fortress and the ships supplying it, but British submarines start from a forward base beside the routes used by German forces moving toward Heligoland. Any German surface assault could therefore lose an important ship before reaching the island. A locally based British destroyer flotilla would add anti-submarine patrols while also facing the risk of the entire High Seas Fleet bearing down on it. The watch point shows how the fortress turns Germany's own coastal waters into an immediate undersea battlespace.
Notable Point · 1:40:26-1:42:17
A submarine contest in Germany's coastal waters
German submarines could threaten the fortress, but British submarines based there would begin a war already positioned beside Germany's fleet routes.