Searchlights: illumination, dazzling, and exposure

Naval searchlights combined target finding, illumination, and deliberate dazzling in one conspicuous system. British ships used light against shore gunners and to cover landings during the 1882 bombardment of Alexandria, and searchlights later entered torpedo-boat tactics before the First World War. The same beam that blinded one gun crew could expose the attacking craft to every other weapon in the formation. A searchlight could also be seen from well beyond the range at which it illuminated a useful target. Active radar and sonar create a similar asymmetry because their emissions may reveal the user farther away than the equipment can detect an opponent. An apparently simple lamp therefore offers an early lesson in emissions control and night-fighting tradeoffs.