The mile is an English unit of length of linear measure equal to 5,280 feet, or 1,760 yards, standardised as 1,609.344 metres by international agreement in 1959. With qualifiers, "mile" is used to describe or translate a wide range of units derived from or equivalent to the Roman mile, such as the nautical mile, the Italian mile, the Chinese mile; the Romans divided their mile into 5,000 roman feet but the greater importance of furlongs in pre-modern England meant that the statute mile was made equivalent to 8 furlongs or 5,280 feet in 1593. This form of the mile spread to the British-colonized nations some of which continue to employ the mile; the US Geological Survey now employs the metre for official purposes but legacy data from its 1927 geodetic datum has meant that a separate US survey mile continues to see some use. While most countries replaced the mile with the kilometre when switching to the International System of Units, the international mile continues to be used in some countries, such as Liberia, the United Kingdom, the United States, a number of countries with fewer than one million inhabitants, most of which are UK or US territories, or have close historical ties with the UK or US.
The mile was abbreviated m. in the past but is now sometimes written as mi to avoid confusion with the SI metre. However, derived units, such as miles per hour or miles per gallon, continue to be universally abbreviated as mph and mpg, respectively; the modern English word mile derives from Middle English myl and Old English mīl, cognate with all other Germanic terms for "miles". These derived from apocopated forms of the Latin mīlia or mīllia, the plural of mīle or mīlle "thousand" but used as a clipped form of mīlle passus or passuum, the Roman mile of one thousand paces; the present international mile is what is understood by the unqualified term "mile". When this distance needs to be distinguished from the nautical mile, the international mile may be described as a "land mile" or "statute mile". In British English, the "statute mile" may refer to the present international miles or to any other form of English mile since the 1593 Act of Parliament, which set it as a distance of 1,760 yards.
Under American law, the "statute mile" refers to the US survey mile. Foreign and historical units translated into English as miles employ a qualifier to describe the kind of mile being used but this may be omitted if it is obvious from the context, such as a discussion of the 2nd-century Antonine Itinerary describing its distances in terms of "miles" rather than "Roman miles"; the mile has been variously abbreviated—with and without a trailing period—as m, M, ml, mi. The American National Institute of Standards and Technology now uses and recommends mi in order to avoid confusion with the SI metre and millilitre. However, derived units such as miles per hour or miles per gallon continue to be abbreviated as mph and mpg rather than mi/h and mi/gal. In the United Kingdom road signs use m as the abbreviation for mile though height and width restrictions use m as the abbreviation for the metre, which may be displayed alongside feet and inches; the BBC style holds that "There is no acceptable abbreviation for'miles'" and so it should be spelt out when used in describing areas.
The Roman mile consisted of a thousand paces as measured by every other step—as in the total distance of the left foot hitting the ground 1,000 times. The ancient Romans, marching their armies through uncharted territory, would push a carved stick in the ground after each 1,000 paces. Well-fed and harshly driven Roman legionaries in good weather thus created longer miles; the distance was indirectly standardised by Agrippa's establishment of a standard Roman foot in 29 BC, the definition of a pace as 5 feet. An Imperial Roman mile thus denoted 5,000 Roman feet. Surveyors and specialized equipment such as the decempeda and dioptra spread its use. In modern times, Agrippa's Imperial Roman mile was empirically estimated to have been about 1,617 yards in length. In Hellenic areas of the Empire, the Roman mile was used beside the native Greek units as equivalent to 8 stadia of 600 Greek feet; the mílion continued to be used as a Byzantine unit and was used as the name of the zero mile marker for the Byzantine Empire, the Milion, located at the head of the Mese near Hagia Sophia.
The Roman mile spread throughout Europe, with its local variations giving rise to the different units below. Arising from the Roman mile is the "milestone". All roads radiated out from the Roman Forum throughout the Empire – 50,000 miles of stone-paved roads. At every mile was placed a shaped stone, on, carved a Roman numeral, indicating the number of miles from the center of Rome – the Forum. Hence, one always knew; the Italian mile was traditionally considered a direct continuation of the Roman mile, equal to 1000 paces, although its actual value over time or between regions could vary greatly. It was used in international contexts from the Middle Ages into the 17th century and is thus known as the "geographical mile", although the geographical mile is now a separate standard unit; the Arabic mile was not the common Arabic unit of length. The Arabic mile was, used by medieval geographers and scientists and constituted a kind of precursor to the nautical or geographical mile, it extended the Roman mile to fit an astronomical approximatio
The Black Sea is a body of water and marginal sea of the Atlantic Ocean between the Balkans, Eastern Europe, the Caucasus, Western Asia. It is supplied by a number of major rivers, such as the Danube, Southern Bug, Dniester and the Rioni. Many countries drain into the Black Sea, including Austria, Belarus and Herzegovina, Croatia, Czech Republic, Germany, Moldova, Romania, Serbia, Slovenia and Ukraine; the Black Sea has an area of 436,400 km2, a maximum depth of 2,212 m, a volume of 547,000 km3. It is constrained by the Pontic Mountains to the south, Caucasus Mountains to the east, Crimean Mountains to the north, Strandzha to the southwest, Dobrogea Plateau to the northwest, features a wide shelf to the northwest; the longest east–west extent is about 1,175 km. Important cities along the coast include Batumi, Constanța, Istanbul, Novorossiysk, Ordu, Rize, Sevastopol, Sukhumi, Varna and Zonguldak; the Black Sea has a positive water balance. There is a two-way hydrological exchange: the more saline and therefore denser, but warmer, Mediterranean water flows into the Black Sea under its less saline outflow.
This creates a significant anoxic layer well below the surface waters. The Black Sea drains into the Mediterranean Sea, via the Aegean Sea and various straits, is navigable to the Atlantic Ocean; the Bosphorus Strait connects it to the Sea of Marmara, the Strait of the Dardanelles connects that sea to the Aegean Sea region of the Mediterranean. These waters separate the Caucasus and Western Asia; the Black Sea is connected, to the North, to the Sea of Azov by the Strait of Kerch. The water level has varied significantly. Due to these variations in the water level in the basin, the surrounding shelf and associated aprons have sometimes been land. At certain critical water levels it is possible for connections with surrounding water bodies to become established, it is through the most active of these connective routes, the Turkish Straits, that the Black Sea joins the world ocean. When this hydrological link is not present, the Black Sea is an endorheic basin, operating independently of the global ocean system, like the Caspian Sea for example.
The Black Sea water level is high. The Turkish Straits connect the Black Sea with the Aegean Sea, comprise the Bosphorus, the Sea of Marmara and the Dardanelles; the International Hydrographic Organization defines the limits of the Black Sea as follows: On the Southwest. The Northeastern limit of the Sea of Marmara. In the Kertch Strait. A line joining Cape Takil and Cape Panaghia. Current names of the sea are equivalents of the English name "Black Sea", including these given in the countries bordering the sea: Abkhazian: Амшын Еиқәа, IPA: Adyghe: Хы шӏуцӏэ, IPA: Bulgarian: Черно море, IPA: Crimean Tatar: Къара денъиз, Qara deñiz IPA: Georgian: შავი ზღვა, translit.: shavi zghva, IPA: Laz and Mingrelian: უჩა ზუღა, IPA:, or ზუღა, IPA:, "Sea" Romanian: Marea Neagră, pronounced Russian: Чёрное мо́рe, IPA: Turkish: Karadeniz, IPA: Ukrainian: Чорне море, IPA: Such names have not yet been shown conclusively to predate the 13th century, but there are indications that they may be older. In Greece, the historical name "Euxine Sea", which holds a different meaning, is still used: Greek: Éfxeinos Póntos.
The principal Greek name "Póntos Áxeinos" is accepted to be a rendering of Iranian word *axšaina-, compare Avestan axšaēna-, Old Persian axšaina-, Middle Persian axšēn/xašēn, New Persian xašīn, as well as Ossetic œxsīn. The ancient Greeks, most those living to the north of the Black Sea, subsequently adopted the name and altered it to á-xenos. Thereafter, Greek tradition refers to the Black Sea as the "Inhospitable Sea", Πόντος Ἄξεινος Póntos Áxeinos, first attested in Pindar; the name was considered to be "ominous" and was changed into the euphemistic name "Hospitable sea", Εὔξεινος Πόντος Eúxeinos Póntos, for the first time attested in Pindar. This became the used designation for the sea in Greek. In contexts related to mythology, the older form Póntos Áxeinos remained favored, it has been erroneously suggested that the name was derived from the color of the water, or was at least related to climatic conditions. Black or dark in this context, referred to a system in which colors represent the cardinal points of the known world.
Black or dark represented the north. The symbolism based on cardinal points was used in multiple occasions and is therefore attested. For example, the "Red Sea", a body of water reported since the time of Herodotus in fact designated the Indian Ocean, together with bodies of water now known as the Persian Gulf and the Red Sea. According to the same explanation and reasoning, it is therefore considered to be impossible
The Finnish Navy is one of the branches of the Finnish Defence Forces. The navy employs about 4,300 conscripts are trained each year. Finnish Navy vessels are given the ship prefix "FNS", short for "Finnish Navy ship", but this is not used in Finnish language contexts; the Finnish Navy includes coastal forces and coastal artillery. The current Commander-in-Chief of the navy is Rear Admiral Kari Takanen; the navy is organized into four Brigade-level units. The navy includes, since 1998 the Nyland Brigade, where Finnish Marines or Coastal Jaegers are trained. Nyland Brigade is the only Swedish language unit in the country and it carries on the traditions and battle-honours of the Nyland Regiment of the Swedish Army. Navy Command headquarters: Naval depot: Pansio and Kimito Naval research depot: Espoo Coastal Brigade: Coastal Fleet: Nyland Brigade: Naval Academy: Two fast attack craft squadrons Three mine countermeasures squadrons Two minelayers Three auxiliary minelayers Two patrol craft Two coastal jaeger battalions Six coastal jaeger companies Two coastal missile companies Four anti-ship missile batteries Four fixed coastal artillery units Twelve mobile coastal artillery unitsTotal of 31,500 personnel During the Swedish era, the Finnish Gulf saw many battles between the Swedish and Russian fleets.
Many of the Swedish naval bases were located in present-day Finland and many sailors came from Finland. During the Russian rule an Finnish Navy unit, named Suomen Meriekipaasi was defending the Finnish coast, alongside the Baltic Fleet of the Imperial Russian Navy; the Meriekipaasi participated in the Crimean War, albeit with on-shore duties. The Meriekipaasi manned the coastal batteries at the Santahamina Island during the siege of fortress Viapori in Helsinki; the ships the Meriekipaasi operated included the steam frigates Rurik and Kalevala, named after the Finnish national epic. These ships served in the Russian Pacific Fleet); the first ships that the independent Finnish Navy obtained were a mix of obsolete vessels left behind by the Russians during the Finnish Civil War and vessels, who had not been able to make the winter voyage to Kronstadt as the Russian Navy retreated from German forces. Thus, the Finnish Navy of the late 1910s and early 1920s consisted of some gunboats, six S-class torpedo boats, eight C-class torpedo boats, one minelayer, several minesweepers, five T-class minelaying boats.
In addition to the warships, the Russians left behind numerous other types of vessels. Additionally, the Germans handed over two netlayers to the Finnish Navy, these two ships formed the core of the Finnish Navy until the coastal defense ships were commissioned. With the Treaty of Tartu, Finland had to return some of the equipment; this equipment included three S-class torpedo boats, the minesweepers Altair, Mikula, MP 7, MP 11, Ahvola, T 12, fifteen tugs, four smaller transports and 54 motorboats. Finland lost three more ships in supporting the British operations against the Soviets in the Baltic Sea; the three vessels were ordered to stay until the sea froze over, were damaged beyond repair by the ice. The last remaining C-class torpedo boats was placed in reserve after this incident. In 1927, after years of wrangling with various plans for how to modernize the navy, due to the loss of the torpedo boat S2 in heavy seas in October 1925, the Parliament of Finland approved a plan to build two coastal defence ships, as well as four submarines.
Motor torpedo boats were acquired both from Britain, as well as from domestic sources. New minesweepers were constructed; the training ship Suomen Joutsen was acquired. The strength of the Finnish Navy at the beginning of World War II was limited; some of the planned ships had not yet been constructed and wartime constraints on the economy prolonged ship building times. The Finnish Navy operated the following vessels in the Baltic Sea: Two coastal defence ships Five submarines Four gunboats Seven motor torpedo boats One minelayer Eight minesweepers One training ship Suomen JoutsenOn Lake Ladoga, the Finns operated: One icebreaker One gunboat One minelayer One tug Two motor boats The navy had several auxiliary warships, ice-breakers and patrol boats from the coast guard; when the Winter War broke out the Finnish Navy moved to occupy the de-militarized Åland Islands and to protect merchant shipping. In the first month of the war, battles between Soviet ships and Finnish coastal batteries were fought at Hanko, Finland, Utö and Koivisto.
At Koivisto and Hanko, the batteries forced Soviet battleships to retire with damage. Finnish efforts to use submarines to sink Soviet capital ships failed. In December 1939 the ice became so thick; the two coastal defence ships were moved to the harbour in Turku where they were used to strengthen the air-defences of the city. They remained there for the rest of the war. Before the Continuation War five more torpedo boats were ordered from Italy; the base that the Soviets had acquired after the Winter War at the Hanko Peninsula divided the areas where the Finnish Navy would operate in two. This i
Siemens-Schuckert was a German electrical engineering company headquartered in Berlin and Nuremberg, incorporated into the Siemens AG in 1966. Siemens Schuckert was founded in 1903 when Halske acquired Schuckertwerke. Subsequently, Siemens & Halske specialized in communications engineering and Siemens-Schuckert in power engineering and pneumatic instrumentation. During World War I Siemens-Schuckert produced aircraft, it took over manufacturing of the renowned Protos vehicles in 1908. In World War II, the company had a factory producing aircraft and other parts at Monowitz near Auschwitz. There was a workers camp near the factory known as Bobrek concentration camp; the Siemens Schuckert logo consisted of an S with a smaller S superimposed on the middle with the smaller S rotated left by 45 degrees. The logo was used into the late 1960s, when both companies merged with the Siemens-Reiniger-Werke AG to form the present-day Siemens AG. Siemens-Schuckert built a number of designs in inter-war era, they produced aircraft engines under the Siemens-Halske brand, which evolved into their major product line after the end of World War I.
The company reorganized as Brandenburgische Motorenwerke, or Bramo, in 1936, were purchased in 1939 by BMW to become BMW Flugmotorenbau. Siemens-Schuckert designed a number of heavy bombers early in World War I, building a run of seven Riesenflugzeug. Intended to be used in the strategic role in long duration flights, the SSW R-series had three 150 h.p Benz Bz. III engines in the cabin driving two propellers connected to a common gear-box through a combination leather-cone and centrifugal-key clutch in SSW R. I to the SSW R. VII models. In the case of engine failure, common at the time, the bomber could continue flying on two engines while the third was repaired by the in-flight mechanic. Two transmission shafts transferred the power from the gear-box to propeller gear-boxes mounted on the wing struts. Although there were some problems with the clutch system, the gear-box proved to be reliable when properly maintained; the SSW R.1 through the SSW R. VII designs were noted for their distinctive forked fuselage.
Several of these aircraft fought on the Eastern Front. Although interesting in concept, the cost of these and the R-types from other companies was so great that the air force abandoned the concept until more practical designs arrived in the war; the first fighter designed at the works was the Siemens-Schuckert E. I which appeared in mid 1915, was the first aircraft to be powered by the Siemens-Halske Sh. I, a new rotary, developed by Siemens-Schuckert, in which the cylinders and the propeller rotated in opposite directions. A small number of production machines were supplied to various Feldflieger Abteilung to supplement supplies of the Fokker and Pfalz monoplane fighters used at the time for escort work; the prototype SSW E. II, powered by the inline Argus AsII, crashed in June 1916, killing Franz Steffen, one of the designers of the SSW R types. By early 1916 the first generation of German monoplane fighters were outclassed by the Nieuport 11 and the Nieuport 17 which quickly followed it; the resulting SSW D.
I was powered by the Siemens-Halske Sh. I, but was otherwise a literal copy of the Nieuport 17; this aircraft was the first Siemens-Schuckert fighter to be ordered in quantity, but by the time it became available in numbers it was outclassed by contemporary Albatros fighters. Development of the Sh. I 160 hp Sh. III one of the most advanced rotary engine designs of the war; the D. I fighter formed the basis for a series of original designs, which by the end of 1917 had reached a peak in the Siemens-Schuckert D. III, which went into limited production in early 1918, found use in home defense units as an interceptor, due to its outstanding rate of climb. Further modifications improved its handling and performance to produce the Siemens-Schuckert D. IV. Several offshoots of the design included triplanes and a parasol monoplane. With the end of the war production of the D. IV continued for sales to Switzerland who flew them into the late 1920s. With the signing of the Treaty of Versailles the next year all aircraft production in Germany was shut down.
Siemens-Schuckert disappeared, but Siemens-Halske continued sales of the Sh. III and started development of smaller engines for the civilian market. By the mid-1920s their rotary engines were no longer in vogue, but "non-turning" versions of the same basic mechanicals led to a series of 7-cylinder radial engines, the Sh.10 through Sh.14A, delivering up to 150 hp in the 14A. The Sh.14A became a best-seller in the trainer market, over 15,000 of all the versions were built. Siemens-Halske no longer had any competitive engines for the larger end of the market, to address this they negotiated a license in 1929 to produce the 9-cylinder Bristol Jupiter IV. Minor changes for the German market led to the Sh.20 and Sh.21. Following the evolution of their smaller Sh.14's, the engine was bored out to produce the 900 hp design, the Sh.22. In 1933 new engine naming was introduced by the RLM, this design became the Sh.322, when Siemens was given the 300-block of numbers. The Sh.322 design never became popular.
The company reorganized as Bramo in 1936, continued development of what was now their own large engine. Modifying the Sh.322 with the addition of fuel injection and a new supercharger led to the Bramo 323 Fafnir, which entered production in 1937. Although ra
The Netherlands is a country located in Northwestern Europe. The European portion of the Netherlands consists of twelve separate provinces that border Germany to the east, Belgium to the south, the North Sea to the northwest, with maritime borders in the North Sea with Belgium and the United Kingdom. Together with three island territories in the Caribbean Sea—Bonaire, Sint Eustatius and Saba— it forms a constituent country of the Kingdom of the Netherlands; the official language is Dutch, but a secondary official language in the province of Friesland is West Frisian. The six largest cities in the Netherlands are Amsterdam, The Hague, Utrecht and Tilburg. Amsterdam is the country's capital, while The Hague holds the seat of the States General and Supreme Court; the Port of Rotterdam is the largest port in Europe, the largest in any country outside Asia. The country is a founding member of the EU, Eurozone, G10, NATO, OECD and WTO, as well as a part of the Schengen Area and the trilateral Benelux Union.
It hosts several intergovernmental organisations and international courts, many of which are centered in The Hague, dubbed'the world's legal capital'. Netherlands means'lower countries' in reference to its low elevation and flat topography, with only about 50% of its land exceeding 1 metre above sea level, nearly 17% falling below sea level. Most of the areas below sea level, known as polders, are the result of land reclamation that began in the 16th century. With a population of 17.30 million people, all living within a total area of 41,500 square kilometres —of which the land area is 33,700 square kilometres —the Netherlands is one of the most densely populated countries in the world. It is the world's second-largest exporter of food and agricultural products, owing to its fertile soil, mild climate, intensive agriculture; the Netherlands was the third country in the world to have representative government, it has been a parliamentary constitutional monarchy with a unitary structure since 1848.
The country has a tradition of pillarisation and a long record of social tolerance, having legalised abortion and human euthanasia, along with maintaining a progressive drug policy. The Netherlands abolished the death penalty in 1870, allowed women's suffrage in 1917, became the world's first country to legalise same-sex marriage in 2001, its mixed-market advanced economy had the thirteenth-highest per capita income globally. The Netherlands ranks among the highest in international indexes of press freedom, economic freedom, human development, quality of life, as well as happiness; the Netherlands' turbulent history and shifts of power resulted in exceptionally many and varying names in different languages. There is diversity within languages; this holds for English, where Dutch is the adjective form and the misnomer Holland a synonym for the country "Netherlands". Dutch comes from Theodiscus and in the past centuries, the hub of Dutch culture is found in its most populous region, home to the capital city of Amsterdam.
Referring to the Netherlands as Holland in the English language is similar to calling the United Kingdom "Britain" by people outside the UK. The term is so pervasive among potential investors and tourists, that the Dutch government's international websites for tourism and trade are "holland.com" and "hollandtradeandinvest.com". The region of Holland consists of North and South Holland, two of the nation's twelve provinces a single province, earlier still, the County of Holland, a remnant of the dissolved Frisian Kingdom. Following the decline of the Duchy of Brabant and the County of Flanders, Holland became the most economically and politically important county in the Low Countries region; the emphasis on Holland during the formation of the Dutch Republic, the Eighty Years' War and the Anglo-Dutch Wars in the 16th, 17th and 18th century, made Holland serve as a pars pro toto for the entire country, now considered either incorrect, informal, or, depending on context, opprobrious. Nonetheless, Holland is used in reference to the Netherlands national football team.
The region called the Low Countries and the Country of the Netherlands. Place names with Neder, Nieder and Nedre and Bas or Inferior are in use in places all over Europe, they are sometimes used in a deictic relation to a higher ground that consecutively is indicated as Upper, Oben, Superior or Haut. In the case of the Low Countries / Netherlands the geographical location of the lower region has been more or less downstream and near the sea; the geographical location of the upper region, changed tremendously over time, depending on the location of the economic and military power governing the Low Countries area. The Romans made a distinction between the Roman provinces of downstream Germania Inferior and upstream Germania Superior; the designation'Low' to refer to the region returns again in the 10th century Duchy of Lower Lorraine, that covered much of the Low Countries. But this time the corresponding Upper region is Upper Lorraine, in nowadays Northern France; the Dukes of Burgundy, who ruled the Low Countries in the 15th century, used the term les pays de par deçà for the Low Countries as opposed to les pays de par delà for their original
A submarine is a watercraft capable of independent operation underwater. It differs from a submersible, it is sometimes used or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. Although experimental submarines had been built before, submarine design took off during the 19th century, they were adopted by several navies. Submarines were first used during World War I, are now used in many navies large and small. Military uses include attacking enemy surface ships, attacking other submarines, aircraft carrier protection, blockade running, ballistic missile submarines as part of a nuclear strike force, conventional land attack, covert insertion of special forces. Civilian uses for submarines include marine science, salvage and facility inspection and maintenance. Submarines can be modified to perform more specialized functions such as search-and-rescue missions or undersea cable repair. Submarines are used in tourism, for undersea archaeology.
Most large submarines consist of a cylindrical body with hemispherical ends and a vertical structure located amidships, which houses communications and sensing devices as well as periscopes. In modern submarines, this structure is the "sail" in American usage and "fin" in European usage. A "conning tower" was a feature of earlier designs: a separate pressure hull above the main body of the boat that allowed the use of shorter periscopes. There is a propeller at the rear, various hydrodynamic control fins. Smaller, deep-diving and specialty submarines may deviate from this traditional layout. Submarines use diving planes and change the amount of water and air in ballast tanks to change buoyancy for submerging and surfacing. Submarines have one of the widest ranges of capabilities of any vessel, they range from small autonomous examples and one- or two-person vessels that operate for a few hours, to vessels that can remain submerged for six months—such as the Russian Typhoon class, the biggest submarines built.
Submarines can work at greater depths than are practical for human divers. Modern deep-diving submarines derive from the bathyscaphe, which in turn evolved from the diving bell. Whereas the principal meaning of "submarine" is an armed, submersible warship, the more general meaning is for any type of submersible craft; the definition as of 1899 was for any type of "submarine boat". By naval tradition, submarines are still referred to as "boats" rather than as "ships", regardless of their size. In other navies with a history of large submarine fleets they are "boats". According to a report in Opusculum Taisnieri published in 1562: Two Greeks submerged and surfaced in the river Tagus near the City of Toledo several times in the presence of The Holy Roman Emperor Charles V, without getting wet and with the flame they carried in their hands still alight. In 1578, the English mathematician William Bourne recorded in his book Inventions or Devises one of the first plans for an underwater navigation vehicle.
A few years the Scottish mathematician and theologian John Napier wrote in his Secret Inventions the following: "These inventions besides devises of sayling under water with divers, other devises and strategems for harming of the enemyes by the Grace of God and worke of expert Craftsmen I hope to perform." It's unclear whether he carried out his idea. The first submersible of whose construction there exists reliable information was designed and built in 1620 by Cornelis Drebbel, a Dutchman in the service of James I of England, it was propelled by means of oars. By the mid-18th century, over a dozen patents for submarines/submersible boats had been granted in England. In 1747, Nathaniel Symons patented and built the first known working example of the use of a ballast tank for submersion, his design used leather bags. A mechanism was used to cause the boat to resurface. In 1749, the Gentlemen's Magazine reported that a similar design had been proposed by Giovanni Borelli in 1680. Further design improvement stagnated for over a century, until application of new technologies for propulsion and stability.
The first military submarine was the Turtle, a hand-powered acorn-shaped device designed by the American David Bushnell to accommodate a single person. It was the first verified submarine capable of independent underwater operation and movement, the first to use screws for propulsion. In 1800, France built a human-powered submarine designed by the Nautilus; the French gave up on the experiment in 1804, as did the British when they considered Fulton's submarine design. In 1864, late in the American Civil War, the Confederate navy's H. L. Hunley became the first military submarine to sink an enemy vessel, the Union sloop-of-war USS Housatonic. In the aftermath of its successful attack against the ship, the Hunley sank because it was too close to its own exploding torpedo. In 1866, the Sub Marine Explorer was the first submarine to dive, cruise underwater, resurface under the control of the crew; the design by German American Julius H. Kroehl incorporated elements that are still used in modern submarines.
In 1866, the Flach was built at the request of the Chilean government, by Karl Flach, a German engineer and immigrant
U-boat is an anglicised version of the German word U-Boot, a shortening of Unterseeboot "underseaboat." While the German term refers to any submarine, the English one refers to military submarines operated by Germany in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most used in an economic warfare role and enforcing a naval blockade against enemy shipping; the primary targets of the U-boat campaigns in both wars were the merchant convoys bringing supplies from Canada and other parts of the British Empire, from the United States to the United Kingdom and to the Soviet Union and the Allied territories in the Mediterranean. German submarines destroyed Brazilian merchant ships during World War II, causing Brazil to declare war on the Axis powers in 1944. Austro-Hungarian Navy submarines were known as U-boats; the first submarine built in Germany, the three-man Brandtaucher, sank to the bottom of Kiel harbor on 1 February 1851 during a test dive.
The inventor and engineer Wilhelm Bauer had designed this vessel in 1850, Schweffel & Howaldt constructed it in Kiel. Dredging operations in 1887 rediscovered Brandtaucher. There followed in 1890 the boats WW2, built to a Nordenfelt design. In 1903 the Friedrich Krupp Germaniawerft dockyard in Kiel completed the first functional German-built submarine, which Krupp sold to Russia during the Russo-Japanese War in April 1904; the SM U-1 was a redesigned Karp-class submarine and only one was built. The Imperial German Navy commissioned it on 14 December 1906, it had a double hull, a Körting kerosene engine, a single torpedo tube. The 50%-larger SM U-2 had two torpedo tubes; the U-19 class of 1912–13 saw the first diesel engine installed in a German navy boat. At the start of World War I in 1914, Germany had 48 submarines of 13 classes in service or under construction. During that war the Imperial German Navy used SM U-1 for training. Retired in 1919, it remains on display at the Deutsches Museum in Munich.
On 5 September 1914, HMS Pathfinder was sunk by SM U-21, the first ship to have been sunk by a submarine using a self-propelled torpedo. On 22 September, U-9 under the command of Otto Weddigen sank the obsolete British warships HMS Aboukir, HMS Cressy and HMS Hogue in a single hour. In the Gallipoli Campaign in early 1915 in the eastern Mediterranean, German U-boats, notably the U-21, prevented close support of allied troops by 18 pre-Dreadnought battleships by sinking two of them. For the first few months of the war, U-boat anticommerce actions observed the "prize rules" of the time, which governed the treatment of enemy civilian ships and their occupants. On 20 October 1914, SM U-17 sank the SS Glitra, off Norway. Surface commerce raiders were proving to be ineffective, on 4 February 1915, the Kaiser assented to the declaration of a war zone in the waters around the British Isles; this was cited as a retaliation for British minefields and shipping blockades. Under the instructions given to U-boat captains, they could sink merchant ships potentially neutral ones, without warning.
In February 1915, a submarine U-6 was rammed and both periscopes were destroyed off Beachy Head by the collier SS Thordis commanded by Captain John Bell RNR after firing a torpedo. On 7 May 1915, SM U-20 sank the liner RMS Lusitania; the sinking claimed 1,198 lives, 128 of them American civilians, the attack of this unarmed civilian ship shocked the Allies. According to the ship's manifest, Lusitania was carrying military cargo, though none of this information was relayed to the citizens of Britain and the United States who thought that the ship contained no ammunition or military weaponry whatsoever and it was an act of brutal murder. Munitions that it carried were thousands of crates full of ammunition for rifles, 3-inch artillery shells, various other standard ammunition used by infantry; the sinking of the Lusitania was used as propaganda against the German Empire and caused greater support for the war effort. A widespread reaction in the U. S was not seen until the sinking of the ferry SS Sussex.
The sinking occurred in 1915 and the United States entered the war in 1917. The initial U. S. response was to threaten to sever diplomatic ties, which persuaded the Germans to issue the Sussex pledge that reimposed restrictions on U-boat activity. The U. S. reiterated its objections to German submarine warfare whenever U. S. civilians died as a result of German attacks, which prompted the Germans to reapply prize rules. This, removed the effectiveness of the U-boat fleet, the Germans sought a decisive surface action, a strategy that culminated in the Battle of Jutland. Although the Germans claimed victory at Jutland, the British Grand Fleet remained in control at sea, it was necessary to return to effective anticommerce warfare by U-boats. Vice-Admiral Reinhard Scheer, Commander in Chief of the High Seas Fleet, pressed for all-out U-boat war, convinced that a high rate of shipping losses would force Britain to seek an early peace before the United States could react effectively; the renewed German campaign was effective, sinking 1.4 million tons of shipping between October 1916 and January 1917.
Despite this, the political situation demanded greater pressure, on 31 January 1917, Germany announced that its U-boats would engage in unrestricted submarine warfare beginning 1 February. On 17 March, German submarines sank three American merchant vessels, the U. S. declared wa