They are fighting a defensive, trenchwar, trying to protect their territory, and the thousands of terrified people in it, rather than a guerrilla war, which might suit them better.
This was the first time that we had a situation roughly similar to the First World War where you have a trench warfare and the use of gas of enemy forces.
And how that expression had come from World War I, because if you lit three cigarettes off one match in your foxhole or trench the enemy in his foxhole or trench had three pins of light to triangulate your location and then he blew up everything or maybe just shot you and your two buddies.