Why did World War I require such enormous quantities of artillery ammunition?

World War I required unprecedented quantities of artillery ammunition primarily due to the evolution of military tactics and the development of "quick-firing" technology.12

The introduction of recoil-control systems allowed guns to fire much more rapidly without needing to be resighted after every round. This increased rate of fire, combined with the mobilization of millions of troops, created a massive demand for projectiles.321

Tactically, the war solidified into extensive trench systems protected by barbed wire and underground shelters. To overcome these well-entrenched defenses, commanders relied on tremendous concentrations of heavy artillery to bombard enemy positions. Because defenders could often keep their main forces out of range or in deep dugouts, attackers required millions of rounds to attempt to neutralize these fortifications. This shift toward industrial-scale firepower was so extreme that, for example, British artillery used 23,000 tons of projectiles during a single week-long bombardment at the First Battle of the Somme, a stark contrast to the 100 tons used by Napoleon’s forces at Waterloo.31