Trench warfare
Trench warfare has become archetypically associated with the First World War of 1914–1918, when the Race to the Sea rapidly expanded trench use on the Western Front starting in September 1914. By the end of October 1914 the whole front in Belgium and France had solidified into lines of trenches, which lasted until the last weeks of the war. Mass infantry assaults were futile in the face of artillery fire as well as rapid rifle and machine-gun fire. Both sides concentrated on breaking up enemy attacks and on protecting their own troops by digging deep into the ground. Trench warfare also took place on other fronts, including in Italy and at Gallipoli.
Anti-tank rifle
The first tanks, beginning with the British Mark I launched against the German trenches in World War I, were nearly impregnable to ordinary rifle fire. Most armoured cars were similarly protected, but troops rarely faced armoured cars, as they could not navigate the landscape of trench warfare very well. Though tanks and armoured cars were vulnerable to artillery, mortars, and grenades, infantry was at a significant disadvantage when facing armoured fighting vehicles since they had no effective direct fire weapon, with the exception of the ubiquitous trench mortar, improvised on the spot. In the direct fire mode, this weapon was manhandled by German infantry over the front of a trench wall and fired at low angles by eye at approaching enemy vehicles. Though somewhat effective, these actions were obviously very hazardous to any desperate mortar crew as their exposure could attract enemy fire.