Q-ships, also known as Q-boats, decoy vessels, special service ships, or mystery ships, were heavily armed merchant ships with concealed weaponry, designed to lure submarines into making surface attacks. This gave Q-ships the chance to open fire and sink them.
The Zimmermann telegram was a secret diplomatic communication issued from the German Foreign Office in January 1917 that proposed a military contract between the German Empire and Mexico if the United States entered World War I against Germany. With Germany's aid, Mexico would recover Texas, Arizona, and New Mexico. The telegram was intercepted by British intelligence.
Submarine warfare is one of the four divisions of underwater warfare, the others being anti-submarine warfare, mine warfare and mine countermeasures.
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.
Naval warfare in World War I was mainly characterised by blockade. The Allied Powers, with their larger fleets and surrounding position, largely succeeded in their blockade of Germany and the other Central Powers, whilst the efforts of the Central Powers to break that blockade, or to establish an effective counter blockade with submarines and commerce raiders, were eventually unsuccessful. Major fleet actions were extremely rare and proved less decisive.
A merchant submarine is a type of submarine intended for trade, and being without armaments, it is not considered a warship like most other types of submarines. The intended use would be blockade running, or to dive under Arctic ice.
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.
Type U 151 U-boats were a class of large, long-range submarines initially constructed during World War I to be merchant submarines and later used by the Kaiserliche Marine.
SM U-38 was a German Type U 31 U-boat which operated in the Mediterranean Sea during World War I. It ended up being the third most successful U-boat participating in the war, sinking 134 merchant ships sunk for a total of 287,811 GRT.
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).
SM U-53 was one of the six Type U 51 U-boats of the Imperial German Navy during the First World War. While in command of U-53 her first captain Hans Rose became the 5th ranked German submarine ace of World War I sinking USS Jacob Jones and 87 merchant ships for a total of 224,314 gross register tons (GRT).
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.
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.
The United States entered into World War I in April 1917, more than two and a half years after the war began in Europe.
HMS Laburnum was a Royal Navy Acacia-class sloop built by Charles Connell and Company, Scotstoun. She was scuttled during the fall of Singapore in 1942.
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.
