Unrestricted submarine warfare is a type of naval warfare in which submarines sink merchant ships such as freighters and tankers without warning. The use of unrestricted submarine warfare has had significant impacts on international relations in regards to both the First World War and the Second World War. Its history has been dominated by German decision making.
There have been attempts to limit the use of unrestricted naval warfare, with some dating back to before the turn of the 20th century as an extension of rules for surface raiders. While initially submarines operated successfully by attacking on the surface using deck guns, attacking without warning while submerged reduces the opportunity for the target to escape or defend itself if armed.
History
German art of the sinking of the Linda Blanche on 30 January 1915 by SM U-21. Passengers and crew are being allowed to disembark into lifeboats, as per cruiser rules.
Customary naval law (specifically, so called cruiser rules) specified that while enemy warships may be attacked freely, civilian and neutral ships can only be interfered with if carrying contraband (announced previously in a contraband list), and the lives of the crew should be protected.[1] Formal limitations on warfare at sea date back to the 1899 Hague Convention.[2]
However, the Imperial German navy was heavily criticised internally by high level officials for their relative inactivity at the start of WWI. To boost the role of the navy, and buoyed by early successes of U-boat warfare, Admiral Tirpitz and Admiral von Pohl suggested a plan whereby U-boats, given a free hand to attack shipping, could potentially force Britain into a "concillatory mood" in as few as six weeks. The admirals appealed to public opinion through press interviews,[3] posing the submarines as "miracle weapons", despite the extremely small number of vessels available. It was believed that a "shock effect" would cause shipping to cease, and that neutrals would judge the campaign a reasonable reprisal for the British naval blockade. Chancellor Bethmann Hollweg accepted this strategy on February 1, 1915, and a directive issued the next day, with a public announcement on the 4th.[4]
This first campaign was not fully unrestricted as it was aimed at Allied vessels, with neutral shipping officially not to be targeted. Many submarine commanders also chose to adhere to cruiser rules anyway. However, the German Admiralty encouraged the U-boats to attack without warning and minimise efforts at identifying targets, as "accidental" sinking of neutral vessels was viewed to have a useful deterrent effect. In the end, the German campaign did not have a significant impact on Britain's goods traffic, but took a heavy civilian toll, including to neutrals. In the most dramatic episode they sank Lusitania in May 1915 in a few minutes, killing over a hundred American passengers.[5] In the face of US anger, German Chancellor Bethmann Hollweg obtained a secret directive to exclude passenger vessels from being targeted and to make strenuous measures to avoid striking neutral vessels, a measure made into a formal and public suspension of unrestricted warfare after the sinking of Arabic in August 1915. Submarines operated under prize rules for 1916 - indeed even during 1915 the majority of attacks were made on the surface.[6]
Admiral Henning von Holtzendorff, chief of the Imperial Admiralty staff, argued successfully in early 1917 to resume unrestricted attacks, at a greater scale than 1915 and thus hopefully successfully starve the British into surrender. The German high command realized the resumption of unrestricted submarine warfare meant war with the United States but calculated that American mobilization would be too slow to stop a German victory on the Western Front.[7][8] The decision made by Germany became one of the "trigger mechanisms" causing the United States, who were previously neutral, to join the war in favour of the British. While initially successful, the U-boats would once again fall short of the hopes of the German Admiralty.[9]
After World War I, there was a strong push to construct international rules prohibiting submarine attacks on merchant ships.[2] In 1922 the United States, the United Kingdom, Japan, France and Italy signed the Washington Treaty on Poison Gas and Submarines, to so restrict the use of submarines as to make them useless as commerce raiders.[10] France did not ratify, so the treaty did not go into effect.
In 1936, states signed the London Protocol on Submarine Warfare. To be deemed acceptable, naval attacks needed to follow prize rules, which called for warships to search merchantmen[11] and place crews in "a place of safety" [12] before sinking them.
Interwar prohibitions on unrestricted submarine warfare have been described as being too unspecified, thus leading to disagreements over how to interpret the rules and agreements.[2] For example, it was unclear what differentiated merchant ships from military ships, in particular given that Britain wanted to retain the rights to arm its merchants.[2] Furthermore, it was considered impractical for small submarines to take on the crews of noncombatant ships due to a lack of space.[2] Crews could be placed in emergency boats, but there was disagreement as to how safe that was.[2]
Prior to World War II, 48 states had accepted the prohibitions on unrestricted submarine warfare, including the great power combatants during World War II.[2] However states rapidly abandoned these restrictions: Mostly significantly Germany with War Order No. 154, and the US from the start of the War in the Pacific.[13]
Instances
There have been four campaigns of unrestricted submarine warfare, one in World War I and three in World War II:
The Pacific War during World War II, between 1941 and 1945, waged between the Allies and Imperial Japan.
The four cases were attempts to impose a naval blockade on countries, especially those heavily dependent on merchant shipping to supply their war industries and feed their populations (such as Britain and Japan). Of these, the US submarine effort was by far the most successful, working together with mines to reduce the Japanese merchant fleet to less than a quarter its initial tonnage.[14]
U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. The term is an anglicized version of the German word U-Boot, a shortening of Unterseeboot, though the German term refers to any submarine. Austro-Hungarian Navy submarines were also known as U-boats.
Submarine warfare is one of the four divisions of underwater warfare, the others being anti-submarine warfare, mine warfare and mine countermeasures.
A tonnage war is a military strategy aimed at merchant shipping. The premise is that the enemy has a finite number of ships and a finite capacity to build replacements. The concept was made famous by German Grand Admiral Karl Dönitz, who wrote:
"The shipping of the enemy powers is one great whole. It is therefore in this connection immaterial where a ship is sunk—it must still in the final analysis be replaced by a new ship".
Hugo von Pohl was a German admiral who served during the First World War. He joined the Navy in 1872 and served in various capacities, including with the new torpedo boats in the 1880s, and in the Reichsmarineamt in the 1890s. He eventually reached the rank of Vizeadmiral and held the position of Chief of the Admiralty Staff in 1913. As Chief of the Admiralty Staff, Pohl was an outspoken advocate of unrestricted submarine warfare, and he put the policy into effect as he left the post on 1 February 1915.
Gulflight was an American 5,189 GRT oil tanker built by the New York Shipbuilding Corporation of Camden, New Jersey for the Gulf Refining Company. It was launched on 8 August 1914. The ship became famous when it was torpedoed early in World War I and became the center of a diplomatic incident which moved the United States closer to war with Germany. The ship survived the attack but was eventually sunk in 1942 by torpedo attack in World War II.
The Thrasher incident, as it became known in US media, was a political and diplomatic incident in 1915, when the United States was still neutral in World War I. On 28 March 1915 the German U-boat U-28 sank the British steamship Falaba by torpedo, killing more than 100 people. One of the victims was a passenger from the US, Leon Chester Thrasher.
SM U-20 was a German Type U 19 U-boat built for service in the Imperial German Navy. She was launched on 18 December 1912, and commissioned on 5 August 1913. During World War I, she took part in operations around the British Isles. U-20 became infamous following her sinking of the British ocean liner RMS Lusitania on 7 May 1915, an act that dramatically reshaped the course of the First World War.
Defensively equipped merchant ship (DEMS) was an Admiralty Trade Division programme established in June 1939, to arm 5,500 British merchant ships with an adequate defence against enemy submarines and aircraft. The acronym DEMS was used to describe the ships carrying the guns, the guns aboard the ships, the military personnel manning the guns, and the shore establishment supporting the system. This followed a similar World War I program of defensively armed merchant ships (DAMS).
Allied submarines were used extensively during the Pacific War and were a key contributor to the defeat of the Empire of Japan.
The Mediterranean U-boat Campaign in the Mediterranean Sea was fought by Austria-Hungary and German Empire against the Allies during World War I. It was characterised by the ability of the Central Powers to raid with near impunity during the first years of the war, causing substantial shipping losses, until the introduction of the convoy system allowed the Allies to drastically cut their losses from 1917 on.
SM UB-10 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I.
SM UB-6 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. The submarine was interned after running aground in neutral Dutch waters, and was scuttled by her crew at Hellevoetsluis.
SS Arabic was a British-registered ocean liner that entered service in 1903 for the White Star Line. She was sunk on 19 August 1915, during the First World War, by German submarine SM U-24, 50 mi (80 km) south of Kinsale, causing a major diplomatic incident.
The U-boat campaign from 1914 to 1918 was the World War I naval campaign fought by German U-boats against the trade routes of the Allies. It took place largely in the seas around the British Isles and in the Mediterranean. The German Empire relied on imports for food and domestic food production and the United Kingdom relied heavily on imports to feed its population, and both required raw materials to supply their war industry; the powers aimed, therefore, to blockade one another. The British had the Royal Navy which was superior in numbers and could operate on most of the world's oceans because of the British Empire, whereas the Imperial German Navy surface fleet was mainly restricted to the German Bight, and used commerce raiders and submarine warfare to operate elsewhere.
The Pless conference was a conference held at the castle of Prince Pless located in the Duchy of Pless on January 8, 1917. The conference involved the German army and navy arguing which division should take command of German activity in World War I. The German navy under Admiral Holtzendorff desired unrestricted submarine warfare to shut down the North Atlantic trade supplying Britain with food and munitions. The navy felt that it could starve Britain within six months to a year, before American troops could arrive on the Western Front and change the war. A memo was drafted by Admiral Holtzendorff in December 1916 before the Pless Conference, that argued for unrestricted submarine warfare. Pressure mounted on Kaiser Wilhem II to agree with the memo, which he had previously disagreed with due to his commitment to a policy of moderation.
The Atlantic U-boat campaign of World War I was the prolonged naval conflict between German submarines and the Allied navies in Atlantic waters—the seas around the British Isles, the North Sea and the coast of France.
SM U-30 was one of 329 U-boat submarines serving in the Imperial German Navy in World War I. She engaged in commerce warfare as part of the First Battle of the Atlantic. U-30 is significant for the torpedoing of the US tanker Gulflight on 1 May 1915 20 nautical miles west of Scilly.
The RMS Lusitania was a British-registered ocean liner that was torpedoed by an Imperial German Navy U-boat during the First World War on 7 May 1915, about 11 nautical miles off the Old Head of Kinsale, Ireland. The attack took place in the declared maritime war-zone around the UK, three months after unrestricted submarine warfare against the ships of the United Kingdom had been announced by Germany following the Allied powers' implementation of a naval blockade against it and the other Central Powers.
Cruiser rules, alternatively called prize rules is a colloquial phrase referring to the conventions regarding the attacking of a merchant ship by an armed vessel. Here cruiser is meant in its original meaning of a ship sent on an independent mission such as commerce raiding. A cruiser in modern naval terminology refers to a type of ship rather than its mission. Cruiser rules govern when it is permissible to open fire on an unarmed ship and the treatment of the crews of captured vessels, and are contrasted to unrestricted submarine warfare where submarines attack without warning and do not act to protect crew.
The 9 January 1917 Crown Council meeting, presided over by German Emperor Wilhelm II, decided on the resumption of unrestricted submarine warfare by the Imperial German Navy during the First World War. The policy had been proposed by the German military in 1916 but was opposed by the civilian government under Chancellor Theobald von Bethmann Hollweg who feared it would alienate neutral powers, including the United States.
References
↑ Mallison, Sally V.; Mallison, W. Thomas (1991). "Naval targeting: lawful objects of attack". International Law Studies. 64.
↑ Steffen, Dirk (2004). "The Holtzendorff Memorandum of 22 December 1916 and Germany's Declaration of Unrestricted U-boat Warfare". The Journal of Military History. 68 (1): 215–224. doi:10.1353/jmh.2003.0412. S2CID159765016. ProjectMUSE50680.
Ronzitti, Natalino (1988). The Law of Naval Warfare: A Collection of Agreements and Documents With Commentaries. Martinus Nijhoff. ISBN978-90-247-3652-2.
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