in military affairs an artificial underground shaft (corridor) of small cross-section (1 by 1.5-2 m) that secretly leads to the fortifications or dispositions of the enemy. Mine galleries were built during attacks on fortresses and during the conduct of underground mine warfare, in order to destroy fortifications by exploding powerful mines. Mine galleries (one or several) were laid out in one or two tiers. The Russian Army made wide use of mine galleries between the 16th and 18th centuries, during the siege of Kazan in 1552, Bendery in 1770, Silistra in 1829, and elsewhere. They were used on a limited scale by various armies during the positional-warfare period of World War I (1914— 18) and very rarely during World War II (1939-45).