Submarine warfare had some impact in the First World War, but became vastly more significant in WWII as the German U-boat packs aimed to blockade Europe.
Submarine warfare had some impact in the First World War, but became vastly more significant in WWII as the German U-boat packs aimed to blockade Europe. Merchant ships took to sailing in large convoys, protected by screens of destroyers and corvettes armed with depth charges and sonar. Daring U-Boat commanders carried out torpedo attacks within the defensive screen, and when several submarines attacked at once, the defenders had little chance of striking back.