MCRP 12-10B.1, page 297

Appendix E Subterranean Operations Knowledge of the nature and location of underground facilities is valuable to both the urban attacker and defender. 1. Tactical Value. Fighting in MOUT is multidimensional. Larger cities may have subterranean features that include sunken garages, underground passages, subway lines, utility tunnels, sewers, and storm drains (Figure E-1). Most of these features allow for the movement of units. Even in smaller European towns, sewers and storm drains permit Marines to move beneath the fighting and surface behind the enemy. Figure E-1. Potential Underground Passages a. Subterranean passages may provide the attacker with covered and concealed routes into and through built-up areas. This may allow an enemy to launch his/her attack along roads that lead into the city while infiltrating a smaller force into the defender’s rear. An enemy unit in the defender’s rear area may disrupt his/her defense and obstruct the avenues of withdrawal for his/her forward defense. b. An attack along a subterranean avenue of approach could become the main effort. Even if the subterranean effort is not immediately successful, it forces the defender to fight on atleast two levels and to extend resources to more than just street-level fighting. c. The existence of subterranean passages forces the defender to defend the built-up area above and below ground. While these passages are usually more of a disadvantage to the defender than to the attacker they may offer some advantages in the defense. When thoroughly reconnoitered and controlled by the defender, subterranean passages provide