In Acceptable Losses, two things stand between your men and open ground:
Defenses
Trench Condition
Let either slip, and enemy pressure builds and recovery becomes harder.
Defenses
Defenses come in many forms, but the most critical is barbed wire. The enemy will probe your perimeter and cut it wherever they can. Gaps widen quickly, and once they do, enemy assaults become more effective.
Defenses do not maintain themselves. Squads must be assigned to the appropriate missions to keep the wire intact and ensure your defenses hold.
Trenches
A good trench keeps your men alive. A bad trench leaves them exposed and wears them down before they even reach the enemy.
The environment damages trenches just as much as the enemy. Rain, wear, and time all degrade trench condition. Poor conditions also reduce your soldiers’ ability to recover.
Bottom Line
Defenses slow the enemy. Trenches protect your men. If either is neglected, the situation deteriorates quickly.