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They also normally could not spare crew members to act as a prize crew and had no capacity to take interned merchant crew members onboard the submarine. Submarine captains put their vessels and crew members at risk by carrying out these rules when they surfaced to conduct an inspection. Accordingly, the rules mandated that naval vessels had to stop and search the merchant vessel and account for the safety of the crew, either by taking them on the warship, providing a prize crew to lead the merchant vessel to a friendly port, or by putting them into life boats in close proximity to land. While submarines could attack warships without warning, internationally recognized Prize Law prescribed a relatively strict set of norms for naval vessels capturing or sinking enemy merchant vessels. Additionally, by early 1915 the Royal Navy had largely neutralized the German surface raider threat to merchant shipping. When the war opened in 1914, Britain possessed the largest submarine force with seventy-five boats, while France and Germany had fifty and thirty, respectively.Īs the stalemate developed on the Western Front and Britain’s blockade of German trade became increasingly effective, German naval leaders explored the idea of using submarines as commerce raiders.
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Armed with effective torpedoes and a mine-laying capability, they served as coastal defense weapon systems and posed a threat to even the most powerful warships of the enemy. The world’s major naval powers began fielding “modern” submarines in the decade leading up to the First World War.
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