Trench Warfare

Trench warfare is a type of warfare in which both armies dig into the ground and create elaborate fortifications. These protect soldiers but tend to prevent large movements. In the long run, trench warfare tends to cause high casualties as there are no flanks to turn and frontal attacks against fixed fortifications are very costly. Living conditions for the soldiers are also unpleasant.

The end of the Civil War, particularly the Petersburg campaign was marked by trench warfare, and it hit its stride during World War I. After that the introduction of portable radios, tanks, and air power made fixed defenses less dominating.