Shelter

Shelter 

(cover), a manmade structure or natural terrain feature, such as a mine, hillside, canyon, ravine, forest, or cave, used to protect military personnel and equipment from enemy fire and bad weather or to provide concealment. Shelters include pits, trenches, dugouts, equipment emplacements, various types of underground structures, and local residential, industrial, and administrative buildings. Cut-and-cover shelters consisting of a pit, one or two ramps for entry and exit, and breastworks are used to conceal combat equipment and vehicles.

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Shelter 

a specially constructed or equipped structure for the protection of military personnel and civilians from artillery shells, bombs, shock waves from atomic explosions, and toxic and radioactive substances. Shelters are classified as light, reinforced, or heavy, depending on the degree of protection afforded, and as small, medium-size, or large, depending on the capacity. Shelters were first used during World War I. Experience gained at that time was later widely used in building bomb shelters and gas shelters before World War II. Such shelters were built in the basements of residences and public buildings in all the major cities of Europe; they were also specially erected in a system of defensive positions during the construction of fortified areas and lines. During World War II, various types of shelter were used in combat to protect soldiers, staff, and medical facilities from artillery shells and bombs; in cities and smaller population centers, they were used to protect civilians.