Submarine shock shapes British cruiser caution

The Royal Navy's habitual zigzagging grew from its First World War fear of submarine attack, especially the shock of losing HMS Aboukir, HMS Cressy, and HMS Hogue in one day. Cruisers carried ASDIC or hydrophones primarily to detect submarines, torpedoes, and other underwater threats, rather than to become routine submarine hunters. Small light cruisers could still join a hunt when no second escort was available. In that case the cruiser could hold or fix the contact while a destroyer ran in to attack with depth charges. This division mattered because the attacking ship could lose ASDIC contact at close range, so an offset sensor platform improved the chance of a successful run.