Throughout history, subterranean operations have been part of warfare. The effect of subterranean warfare has had varying levels of significance dependent on the battle, campaign, or war. Large defensive walls constructed around cities have been in use for thousands of years. During periods of invasion or siege, tunnel systems were often dug to permit escape and passage of water or supplies beyond enemy lines. Castles and fortresses during the middle ages provided formidable protection against enemies, and engineers were required to devise siege engines and sabotage tunnel systems to collapse walls and breach defenses. In the American Civil War, tunnel systems were used on more than one occasion.
DesignationATP 3-21.51
EditionNov 2019
StatusActive
ProponentTRADOC
Pages228
FunctionSmall Unit Tactics
CollectionCurrent Doctrine
Approved for public release; distribution is unlimited. This publication supersedes ATP 3-21.51, dated 21 February 2018