Coastal defence (Commonwealth), Coastal defense (US) and Coastal fortification are measures taken to provide protection against attack by military and naval forces at or near the shoreline. Because an invading enemy normally required a port or harbour to sustain operations, such defences are usually concentrated around such facilities, or places where such facilities could be constructed.[1]
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China first established formal coastal defences during the early Ming dynasty (14th century) to protect against attacks by pirates (wokou). Coastal defences were maintained through both the Ming dynasty and the Qing dynasty that followed, protecting the coast against pirates, and against the Portuguese and other European powers that sought to impose their will on China.[2][2]
Subsequently, the European powers built their own coastal defences to protect the various colonial enclaves that they established along the Chinese coast. One such, a fort built by the British commanding the Lei Yue Mun channel between Hong Kong Island and the mainland, has been converted into the Hong Kong Museum of Coastal Defence. This tells the story of coastal defence along the South China coast from the Ming dynasty onwards.[2]
The coastline of New Zealand was fortified in two main waves. The first wave occurred around 1885 and was a response to fears of an attack by Russia. The second wave occurred during World War II and was due to fears of invasion by the Japanese.[3]
The fortifications were built from British designs adapted to New Zealand conditions. These installations typically included gun emplacements, pill boxes, fire command or observation posts, camouflage strategies, underground bunkers, sometimes with interconnected tunnels, containing magazines, supply and plotting rooms and protected engine rooms supplying power to the gun turrets and searchlights.[3]
The defence of its coasts was a major concern for the United States from its independence. Prior to the American Revolution many coastal fortifications already dotted the Atlantic coast, as protection from pirate raids and foreign incursions. The Revolution led to the construction of many additional fortifications, mostly comprising simple earthworks erected to meet specific threats.[1]
The prospect of war with European powers in the 1790s led to a national programme of fortification building spanning seventy years in three phases, known as the First, Second and Third Systems. By the time of the American Civil War, advances in armour and weapons had made masonry forts obsolete, and the combatants discovered that their steamships and ironclad warships could penetrate Third System defences with acceptable losses.[1][4]
In 1885 US President Grover Cleveland appointed the Endicott Board, whose recommendations would lead to a large-scale modernization programme of harbour and coastal defences in the United States, especially the construction of well dispersed, open topped reinforced concrete emplacements protected by sloped earthworks. Many of these featured disappearing guns, which sat protected behind the walls, but could be raised to fire. Mine fields were a critical component of the defence, and smaller guns were also employed to protect the mine fields from minesweeping vessels.[1]
The development of military aviation rendered these open topped emplacements vulnerable to air attack. Therefore, the next, and last, generation of coastal artillery was mounted under thick concrete shields covered with vegetation to make them virtually invisible from above. In anticipation of a conflict with Japan, most of the limited funds available between 1933 and 1938 were spent on the Pacific coast. In 1939 the threat of war in Europe prompted larger appropriations and the resumption of work along the Atlantic coast.[1]