FM/BG-1119 - Principles of defending
- Security: Observation of all avenues of approach must be maintained. Sentries, OPs, and rear/flank watch are essential. Without 360° awareness, the defense is vulnerable to surprise and flanking.
- Positioning: Every position should offer cover from fire, concealment from observation, and effective fields of fire. Terrain and fortifications must be used to the defender’s advantage, while minimizing exposure to likely threat angles.
- Depth: A layered defense absorbs shocks and enables fallback. Forward elements slow the enemy, while reserves counterattack or hold rear lines. Depth provides both resilience and flexibility.
- Mutual Support: Defensive positions must overlap in fields of fire, allowing them to support one another. No position should be isolated; any attack on one should trigger fire from others.
- Flexibility: Plans must account for contingencies. Have fallback positions, repositioning routes, and mobile reserves. Defenses that cannot adapt are easily overrun.