Royal Navy ships zigzagged, varied speed, and commonly carried at least hydrophones, with many equipped with ASDIC. That defensive equipment could become offensive when cruisers such as HMS Hermione actively hunted submarines. The habit reflected the shock of the First World War, when submarines sank major British cruisers and exposed the cost of inadequate preparation. Anti-submarine warfare had become a fleet-wide practice shaped by institutional memory rather than a specialist escort task.
Notable Point · 28:23-30:41
Royal Navy cruisers carried anti-submarine lessons into battle
Hydrophones and ASDIC made even British cruisers dangerous submarine opponents, reflecting institutional lessons drawn from First World War losses.