SM U-151 or SM Unterseeboot 151 was a World War I U-boat of the Imperial German Navy, constructed by Reiherstieg Schiffswerfte & Maschinenfabrik at Hamburg and launched on 4 April 1917. From 1917 until the Armistice in November 1918 she was part of the U-Kreuzer Flotilla, and was responsible for 34 ships sunk (88,395 GRT) and 7 ships damaged.
HMS Salmon was a second-batch S-class submarine built during the 1930s for the Royal Navy. Completed in 1935, the boat fought in the Second World War. Salmon is one of twelve boats named in the song "Twelve Little S-Boats".
SM U-14 or U-XIV was a U-boat or submarine of the Austro-Hungarian Navy during the First World War. She was launched in 1912 as the French Brumaire-class submarineCurie, but captured and rebuilt for service in the Austro-Hungarian Navy. At war's end, the submarine was returned to France and restored to her former name.
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.
Deutschland was a blockade-breaking German merchant submarine used during World War I. It was developed with private funds and operated by the North German Lloyd Line. She was the first of seven U-151-class U-boats built and one of only two used as unarmed cargo submarines.
HMS L2 was a L-class submarine built for the Royal Navy during World War I.
SM U-156 was a German Type U 151 U-boat commissioned in 1917 for the Imperial German Navy. From 1917 until her disappearance in September 1918 she was part of the U-Kreuzer Flotilla, and was responsible for sinking 45 ships and damaging two others. She took part in the Attack on Orleans.
HMS Ariel was an Acheron-class destroyer built in 1911, which served during the First World War and sank in 1918 after striking a mine. Named after Shakespeare's "airy spirit", or the biblical spirit of the same name, she was the tenth and last ship of the name to serve in the Royal Navy.
SM U-16 or U-XVI was a U-10-class submarine or U-boat of the Austro-Hungarian Navy during World War I. U-16 was constructed in Germany and shipped by rail to Pola where she was assembled and completed in September 1915. She was commissioned in October 1915.
SM U-20 or U-XX was the lead boat of the U-20 class of submarines or U-boats built for and operated by the Austro-Hungarian Navy during the First World War. The design for U-20 was based on that of the submarines of the Royal Danish Navy's Havmanden class, and was largely obsolete by the beginning of the war.
SM U-66 was the lead ship of the Type U-66 submarines or U-boats for the Imperial German Navy during World War I. The submarine had been laid down in Kiel in November 1913 as U-7, the lead ship of the U-7 class for the Austro-Hungarian Navy. They became convinced after the outbreak of war in August 1914 that none of these submarines could be delivered to the Adriatic via Gibraltar, and sold the entire class, including U-7, to the German Imperial Navy in November 1914.
SM U-70 was a Type U 66 submarine or U-boat for the German Imperial Navy during the First World War. She had been laid down in February 1914 as U-11 the final boat of the U-7 class for the Austro-Hungarian Navy but was sold to Germany, along with the others in her class, in November 1914.
SM UB-16 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. The submarine was sunk by a British submarine in May 1918.
SM UB-17 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. The submarine disappeared during a patrol in March 1918.
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 unrestricted submarine warfare to operate elsewhere.
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-21 was a U-boat built for the Imperial German Navy shortly before World War I. The third of four Type U-19-class submarines, these were the first U-boats in German service to be equipped with diesel engines. U-21 was built between 1911 and October 1913 at the Kaiserliche Werft in Danzig. She was armed with four torpedo tubes and a single deck gun; a second gun was added during her career.
United States Navy operations during World War I began on April 6, 1917, after the formal declaration of war on the German Empire. The United States Navy focused on countering enemy U-boats in the Atlantic Ocean and the Mediterranean Sea while convoying men and supplies to France and Italy. Because of United States's late entry into the war, her capital ships never engaged the German fleet and few decisive submarine actions occurred.
Otto Hersing was a German naval officer who served as U-boat commander in the Kaiserliche Marine and the k.u.k. Kriegsmarine during World War I.
HMS Mantua was a 20th-century ocean liner and armed merchant cruiser. Launched in 1909 as a passenger ship, Mantua was outfitted as an armed merchant cruiser in 1914 and served with the Royal Navy during World War I. On a voyage to Freetown in 1918, the passengers and crew of Mantua inadvertently spread the 1918 flu pandemic to Africa.
German Empire 
