Trench warfare
Trench warfare occurred when a revolution in firepower was not matched by similar advances in mobility, resulting in a grueling form of warfare in which the defender held the advantage. On the Western Front in 1914–1918, both sides constructed elaborate trench, underground, and dugout systems opposing each other along a front, protected from assault by barbed wire, mines, camouflaged trapping pits, and other obstacles. The area between opposing trench lines (known as "no man's land") was fully exposed to artillery fire from both sides. Attacks, even if successful, often sustained severe casualties.
Trench warfare
As far back as the 18th century, Prussian military doctrine stressed maneuver and force concentration to achieve a decisive battle (). The German military searched for ways to apply this in the face of trench warfare. Experiments with new tactics by Willy Rohr, a Prussian captain serving in the Vosges mountains in 1915, got the attention of the Minister of War. These tactics carried Prussian military doctrine down to smallest units — specially trained troops maneuvered and massed to assault positions they chose on their own. During the next 2 years the German army tried to establish special stormtrooper detachments in all its units by sending selected men to Rohr and have those men then train their comrades in their original units.