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.
British Expeditionary Force (World War I)
The Allied retreat finally ended at the River Marne, where Entente forces prepared to make a stand to defend Paris. This led to the First Battle of the Marne, which was fought from 5 to 10 September 1914. This battle would prove to be a major turning point of the war: it denied the Germans an early victory. From 13 September the First Battle of the Aisne took place, with both sides starting to dig trenches. Then for a three-week period following the development of trench warfare each side gave up frontal assaults and began trying to encircle each other's flank. This period became known as the Race to the Sea: the Germans aimed to turn the Allied left flank, and the Allies sought to turn the German right flank.