Dated Nov 2019

ATP 3-21.51, Subterranean Operations, is published to provide urgently needed guidance to plan, prepare for, and execute operations in subterranean environments.

Army Techniques Publication (ATP) 3-21.51 provides doctrinal guidance and direction for all brigade combat teams (BCTs) and their subordinate elements conducting subterranean operations.

Throughout history Armies used subterranean operations to achieve otherwise impossible objectives. Commanders built and used simple supply tunnels under castle fortifications and intricate entrance and exit tunnels to surprise the enemy with an overwhelming mass of force. Subterranean spaces were used to protect vulnerable populations, mission command and medical centers, equipment and supplies, and weapons systems.

Having observed the evolution of our capabilities and tactics, smart, deliberate adversaries made adaptations to counter our considerable strategic and tactical advantages in firepower and detection. Enemy forces continue to build subterranean systems or repurpose existing underground civil infrastructure to move, maneuver, sustain, prevent detection, and protect their assets. There are over 10,000 known military purposed subterranean systems worldwide and most urban cities have a significant civil network of subways, tunnels, and sewers. Similar to stability operations, subterranean systems may also have enemy combatants alongside civilians.

The principal audience for ATP 3-21.51 is all members of the profession of arms.  Trainers and educators throughout the Army will also use this publication.

ATP 3-21.51 applies to the Active Army, Army National Guard/Army National Guard of the United States and United States Army Reserve unless otherwise stated.

This book is a "BIG" (the size of a regular piece of paper) size - Coil binding is used to allow for easy page flipping with no binding.

This website also has this book in "mini" size (half the size of a regular sheet of paper). A popular size to carry anywhere (briefcase, large pocket, purse) but the print is large enough for easy reading.

The Color covers are laminated for weather protection.