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
Artillery dominated the battlefields of trench warfare. An infantry attack was rarely successful if it advanced beyond the range of its supporting artillery. In addition to bombarding the enemy infantry in the trenches, the artillery could be used to precede infantry advances with a creeping barrage, or engage in counter-battery duels to try to destroy the enemy's guns. Artillery mainly fired fragmentation, high-explosive, shrapnel or, later in the war, gas shells. The British experimented with firing thermite incendiary shells, to set trees and ruins alight. However, all armies experienced shell shortages during the first year or two of World War I, due to underestimating their usage in intensive combat. This knowledge had been gained by the combatant nations in the Russo-Japanese War, when daily artillery fire consumed ten times more than daily factory output, but had not been applied.