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.
Battle
Until the 19th century the majority of battles were of short duration, many lasting a part of a day. (The Battle of Preston (1648), the Battle of Nations (1813) and the Battle of Gettysburg (1863) were exceptional in lasting three days.) This was mainly due to the difficulty of supplying armies in the field, or conducting night operations. The means of prolonging a battle was typically by employment of siege warfare. Improvements in transportation and the sudden evolving of trench warfare, with its siege-like nature during World War I in the 20th century, lengthened the duration of battles to days and weeks. This created the requirement for unit rotation to prevent combat fatigue, with troops preferably not remaining in a combat area of operations for more than a month. Trench warfare had become largely obsolete in conflicts between advanced armies by the start of the Second World War.