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British hardened field defences of World War II were small fortified structures constructed as a part of British anti-invasion preparations. They were popularly known as ''pillboxes'', a reference to their shape. ==Design and development== In May 1940, the directorate of Fortifications and Works (FW3) was set up at the War Office under the direction of Major-General G. B. O. Taylor. Its purpose was to provide a number of basic but effective pillbox designs that could be constructed by soldiers and local labour at appropriate defensive locations. In the following June and July FW3 issued six basic designs for rifle and light machine gun, designated Type 22 to Type 27. In addition, there were designs for gun emplacements suitable for either the Ordnance QF 2 pounder or the Hotchkiss 6pdr gun〔Some commentators make reference to the Ordnance QF 6 pounder rather than the older Hotchkiss 6 pdr, but this is in error.〕 (designated Type 28) and a design for a hardened medium machine gun emplacement. There were also designs for pillbox-like structures for various purposes including light anti-aircraft positions, observation posts and searchlight positions to illuminate the shoreline. In addition, the Air Ministry provided designs of fortifications intended to protect airfields from troops landing or parachuting. These would not be expected to face heavy weapons so that the degree of protection was less and there was more emphasis on all-round visibility and sweeping fields of fire. Many of these were later reinforced. Embrasures were available precast and factory produced to standard designs, but as these were in short supply some embrasures were improvised from brick or concrete paving. Embrasures were frequently fitted with a steel or concrete-asbestos shutter. From March 1941, some pillbox embrasures were fitted with a Turnbull mount: this was a metal frame that supported a medium machine gun.〔(【引用サイトリンク】 work= )〕 The degree of protection offered by a pillbox varied considerably: the thickness of the walls and roof generally varied from just 12 in to 3 ft 6 in (0.3 to 1.1m) or more although the commercially produced designs were often much thinner. In March 1940, General Brooke carried out penetration trials and recorded that a anti-tank gun could easily penetrate up to of reinforced concrete.〔Alanbrooke, War Diaries, Entry 22 March 1940.〕 Despite such results the thick-walled pillboxes were designated as shell-proof, whereas the thinner-walled pillboxes were designated as bulletproof. Internally, pillboxes are generally cramped and spartan. Some internal concrete shelves and tables were provided to support weapons and some were whitewashed inside. Only the Type 28s provided a little space — sufficient for a few home comforts. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「British hardened field defences of World War II」の詳細全文を読む スポンサード リンク
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