1911 Encyclopædia Britannica/Blockhouse
BLOCKHOUSE, in fortification, a small roofed work serving as a fortified post for a small garrison. The word, common since 1500, is of uncertain origin, and was applied to what is now called a fort d’arrêt, a detached fort blocking the access to a landing, channel, pass, bridge or defile. The modern blockhouse is a building, sometimes of two storeys, which is loopholed on all sides, and not infrequently, in the case of two-storey blockhouses, provided with a mâchicoulis gallery. Blockhouses are built of wood, brick, stone, corrugated iron or any material available. During the South African War (1899–1902) they were often sent from England to the front in ready-made sections.