Blockhouse

A blockhouse is a small fortification, usually consisting of one or more rooms with loopholes, allowing its defenders to fire in various directions.

[1] It is usually an isolated fort in the form of a single building, serving as a defensive strong point against any enemy that does not possess siege equipment or, in modern times, artillery, air force or cruise missiles.

A fortification intended to resist these weapons is more likely to qualify as a fortress or a redoubt, or in modern times, be an underground bunker.

The term blockhouse is of uncertain origin, perhaps related to Middle Dutch blokhus and 18th-century French blocus (blockade).

Often sited in pairs, the blockhouses were not built to a common design, but usually consisted of a stone tower and bastion or gun platform, which could be semi-circular, rectangular or irregular in shape.

[8] Originally blockhouses were often constructed as part of a large plan, to "block" access to vital points in the scheme.

But from the Age of Exploration to the nineteenth century standard patterns of blockhouses were constructed for defence in frontier areas, particularly South Africa, New Zealand, Canada,[9] and the United States.

[13] These could be prefabricated, delivered to site by armoured train, and then have locally sourced rocks or rubble packed inside the double skin to provide improved protection.

A circular design developed by Major Rice in February 1901 had good all round visibility, and the lack of corners did away with the need for a substructure.

[14] Some blockhouses like those constructed in England in 1940 were built in anticipation of a German invasion; they were often hexagonal in shape and were called "pillboxes".

In Berlin and other cities during World War II some massive blockhouses were built as air-raid shelters and anti-aircraft artillery platforms.

[citation needed] Blockhouses and coordinated road systems were used in the encirclement campaigns of Chiang Kai-shek against the Chinese Communist Party.