A pillbox is a type of blockhouse, or concrete dug-in guard-post, often camouflaged, normally equipped with loopholes through which defenders can fire weapons. It is in effect a trench firing step, hardened to protect against small-arms fire and grenades, and raised to improve the field of fire.
The modern concrete pillbox originated on the Western Front of World War I, in the German Army[1] in 1916.
pill-box [:] A concrete fortification mostly used for machine guns, invented by the Germans.