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Concertina Wire
Concertina wire or Dannert wire is a type of barbed wire or razor wire that is formed in large coils which can be expanded like a concertina. In conjunction with plain barbed wire (and/or razor wire/tape) and steel pickets, it is most often used to form military-style wire obstacles. It is also used in non-military settings, such as when used in prison barriers, detention camps, riot control, or at international borders. During World War I, soldiers manufactured concertina wire themselves, using ordinary barbed wire. Today, it is factory made. Origins In World War I, barbed wire obstacles were made by stretching lengths of barbed wire between stakes of wood or iron. At its simplest, such a barrier would resemble a fence as might be used for agricultural purposes. The double apron fence comprised a line of pickets with wires running diagonally down to points on the ground either side of the fence. Horizontal wires were attached to these diagonals. More elaborate and f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Razor Wire
Barbed tape or razor wire is a mesh of metal strips with sharp edges whose purpose is to prevent passage by humans. The term "razor wire", through long usage, has generally been used to describe barbed tape products. Razor wire is much sharper than the standard barbed wire; it is named after its appearance but is not razor sharp. The points are very sharp and made to rip and snag clothing and flesh. The multiple blades of a razor-wire fence are designed to inflict serious cuts on anyone attempting to climb through or over it and therefore also has a strong psychological deterrent effect. Razor wire is used in many security applications because, although it can be circumvented relatively quickly by humans with tools, penetrating a razor-wire barrier without tools is very slow and typically injurious, often thwarting such attempts or giving security forces more time to respond. Use Starting in the late 1960s, barbed tape was typically found in prisons and secure mental hospita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fortification (obstacles)
A fortification is a military construction or building designed for the defense of territories in warfare, and is also used to establish rule in a region during peacetime. The term is derived from Latin ''fortis'' ("strong") and ''facere'' ("to make"). From very early history to modern times, defensive walls have often been necessary for cities to survive in an ever-changing world of invasion and conquest. Some settlements in the Indus Valley civilization were the first small cities to be fortified. In ancient Greece, large stone walls had been built in Mycenaean Greece, such as the ancient site of Mycenae (famous for the huge stone blocks of its 'cyclopean' walls). A Greek '' phrourion'' was a fortified collection of buildings used as a military garrison, and is the equivalent of the Roman castellum or English fortress. These constructions mainly served the purpose of a watch tower, to guard certain roads, passes, and borders. Though smaller than a real fortress, they ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slinky
The Slinky is a helical spring toy invented by Richard James in the early 1940s. It can perform a number of tricks, including travelling down a flight of steps end-over-end as it stretches and re-forms itself with the aid of gravity and its own momentum, or appear to levitate for a period of time after it has been dropped. These interesting characteristics have contributed to its success as a toy in its home country of the United States, resulting in many popular toys with slinky components in a wide range of countries. History The Slinky was invented and developed by American naval engineer Richard T. James in 1943 and demonstrated at Gimbels department store in Philadelphia in November 1945. The toy was a hit, selling its entire inventory of 400 units in 90 minutes. James and his wife Betty formed James Industries in Clifton Heights, Pennsylvania to manufacture Slinky and several related toys such as the Slinky Dog and Suzie, the Slinky Worm. In 1960, James's wife Betty Jam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helix
A helix () is a shape like a corkscrew or spiral staircase. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices. The word ''helix'' comes from the Greek word ''ἕλιξ'', "twisted, curved". A "filled-in" helix – for example, a "spiral" (helical) ramp – is a surface called ''helicoid''. Properties and types The ''pitch'' of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two (typically congruent) helices with the same axis, differing by a translation along the axis. A circular helix (i.e. one with constant radius) has constant band curvature and constant torsion. A ''conic helix'', also known as a ''conic spiral'', may be defined as a spiral on a conic surface, with the distance to the apex an expo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emperor Constantine
Constantine I ( , ; la, Flavius Valerius Constantinus, ; ; 27 February 22 May 337), also known as Constantine the Great, was Roman emperor from AD 306 to 337, the first one to convert to Christianity. Born in Naissus, Dacia Mediterranea (now Niš, Serbia), he was the son of Flavius Constantius, a Roman army officer of Illyrian origin who had been one of the four rulers of the Tetrarchy. His mother, Helena, was a Greek Christian of low birth. Later canonized as a saint, she is traditionally attributed with the conversion of her son. Constantine served with distinction under the Roman emperors Diocletian and Galerius. He began his career by campaigning in the eastern provinces (against the Persians) before being recalled in the west (in AD 305) to fight alongside his father in Britain. After his father's death in 306, Constantine became emperor. He was acclaimed by his army at Eboracum (York, England), and eventually emerged victorious in the civil wars against emperors ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Anti-invasion Preparations Of World War II
British anti-invasion preparations of the Second World War entailed a large-scale division of military and civilian mobilisation in response to the threat of invasion (Operation Sea Lion) by German armed forces in 1940 and 1941. The British Army needed to recover from the defeat of the British Expeditionary Force in France, and 1.5 million men were enrolled as part-time soldiers in the Home Guard. The rapid construction of field fortifications transformed much of the United Kingdom, especially southern England, into a prepared battlefield. Sea Lion was never taken beyond the preliminary assembly of forces. Today, little remains of Britain's anti-invasion preparations, although reinforced concrete structures such as pillboxes and anti-tank cubes can still be commonly found, particularly in the coastal counties. Political and military background On 1 September 1939, Germany invaded Poland; two days later, Britain and France declared war on Germany, launching the Second World ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platoon
A platoon is a military unit typically composed of two or more squads, sections, or patrols. Platoon organization varies depending on the country and the branch, but a platoon can be composed of 50 people, although specific platoons may range from 10 to 100 people. A platoon is typically the smallest military unit led by a commissioned officer. The platoon leader is usually a junior officer—a second or first lieutenant or an equivalent rank. The officer is usually assisted by a platoon sergeant. Rifle platoons normally consist of a small platoon headquarters and three or four sections (Commonwealth) or squads (United States). In some armies, platoon is used throughout the branches of the army. In a few armies, such as the French Army, a platoon is specifically a cavalry unit, and the infantry use "section" as the equivalent unit. A unit consisting of several platoons is called a company or a battery. Etymology According to Merriam-Webster, "The term was first used in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
No-man's-land
No man's land is waste or unowned land or an uninhabited or desolate area that may be under dispute between parties who leave it unoccupied out of fear or uncertainty. The term was originally used to define a contested territory or a dumping ground for refuse between fiefdoms. In modern times, it is commonly associated with World War I to describe the area of land between two enemy trench systems, not controlled by either side. Coleman p. 268 The term is also used metaphorically, to refer to an ambiguous, anomalous, or indefinite area, in regards to an application, situation, or jurisdiction. It has sometimes been used to name a specific place. Origin According to Alasdair Pinkerton, an expert in human geography at Royal Holloway, University of London, the term is first mentioned in Domesday Book (1086), to describe parcels of land that were just beyond the London city walls. The ''Oxford English Dictionary'' contains a reference to the term dating back to 1320, spell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trench Warfare
Trench warfare is a type of land warfare using occupied lines largely comprising military trenches, in which troops are well-protected from the enemy's small arms fire and are substantially sheltered from artillery. Trench warfare became archetypically associated with World War I (1914–1918), when the Race to the Sea rapidly expanded trench use on the Western Front starting in September 1914.. Trench warfare proliferated when a revolution in firepower was not matched by similar advances in mobility, resulting in a grueling form of warfare in which the defender held the advantage. On the Western Front in 1914–1918, both sides constructed elaborate trench, underground, and dugout systems opposing each other along a front, protected from assault by barbed wire. The area between opposing trench lines (known as " no man's land") was fully exposed to artillery fire from both sides. Attacks, even if successful, often sustained severe casualties. The development of armoured ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
War Office
The War Office was a department of the British Government responsible for the administration of the British Army between 1857 and 1964, when its functions were transferred to the new Ministry of Defence (MoD). This article contains text from this source, which is available under th Open Government Licence v3.0 © Crown copyright It was equivalent to the Admiralty, responsible for the Royal Navy (RN), and (much later) the Air Ministry, which oversaw the Royal Air Force (RAF). The name 'War Office' is also given to the former home of the department, located at the junction of Horse Guards Avenue and Whitehall in central London. The landmark building was sold on 1 March 2016 by HM Government for more than £350 million, on a 250 year lease for conversion into a luxury hotel and residential apartments. Prior to 1855, 'War Office' signified the office of the Secretary at War. In the 17th and 18th centuries, a number of independent offices and individuals were re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concertina Wire
Concertina wire or Dannert wire is a type of barbed wire or razor wire that is formed in large coils which can be expanded like a concertina. In conjunction with plain barbed wire (and/or razor wire/tape) and steel pickets, it is most often used to form military-style wire obstacles. It is also used in non-military settings, such as when used in prison barriers, detention camps, riot control, or at international borders. During World War I, soldiers manufactured concertina wire themselves, using ordinary barbed wire. Today, it is factory made. Origins In World War I, barbed wire obstacles were made by stretching lengths of barbed wire between stakes of wood or iron. At its simplest, such a barrier would resemble a fence as might be used for agricultural purposes. The double apron fence comprised a line of pickets with wires running diagonally down to points on the ground either side of the fence. Horizontal wires were attached to these diagonals. More elaborate and f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
