Sloops or armed trawlers were conspicuously absent from patrols around an anchorage holding capital ships, even though treaty rules allowed Britain to build such vessels. A trawler had helped stop U-18 in 1914, demonstrating the value of a mobile patrol layer before sophisticated sensors. Once Royal Oak's first explosion occurred, a patrol craft searching the harbor could have forced U-47 to evade instead of turning and reloading undisturbed. The critique connects interwar funding choices to a specific operational gap between blockships and the battleship's own damage-control response.
Notable Point · 2:17:47-2:20:57
The missing patrol layer in Royal Oak's defense
The attack exposed gaps in fixed defenses and a shortage of patrol craft able to investigate the first explosion and hunt U-47.