Editing Trench warfare (section)

== Adoption ==
[[File:Bundesarchiv Bild 183-R34771, Frankreich, Arras, Schützengraben.jpg|thumb|left|German forward detachments guarding the entrance to a trench line in front of [[Arras#World War I|Arras]] in 1915]]
[[File:Cheshire Regiment trench Somme 1916.jpg|thumb|right|Trenches of the 11th [[Cheshire Regiment]] at Ovillers-la-Boisselle, on the [[Battle of the Somme|Somme]], July 1916. One sentry keeps watch while the others sleep. Photo by [[Ernest Brooks (photographer)|Ernest Brooks]]]]
[[File:Lancashire Fusiliers trench Beaumont Hamel 1916.jpg|thumb|right|[[Lancashire Fusiliers|1st Lancashire Fusiliers]], in communication trench near [[Beaumont Hamel]], Somme, 1916. Photo by [[Ernest Brooks (photographer)|Ernest Brooks]]]]

Although technology had dramatically changed the nature of warfare by 1914, the armies of the major combatants had not fully absorbed the implications. Fundamentally, as the range and rate of fire of rifled small-arms increased, a defender shielded from enemy fire (in a trench, at a house window, behind a large rock, or behind other cover) was often able to kill several approaching foes before they closed around the defender's position. Attacks across open ground became even more dangerous after the introduction of rapid-firing [[artillery]], exemplified by the [[Canon de 75 modèle 1897|"French 75"]], and [[high explosive]] [[fragmentation (weaponry)|fragmentation]] rounds. The increases in firepower had outstripped the ability of [[infantry]] (or even [[cavalry]]) to cover the ground between firing lines, and the ability of armour to withstand fire. It would take a revolution in mobility to change that.<ref>Dyer, Gwynn. ''War''; Dupuy, Trevor N. ''Evolution of Weapons and Warfare''</ref>

The French and German armies adopted different [[Military tactics|tactical doctrines]]: the French relied on the attack with speed and surprise, and the Germans relied on [[firepower]], investing heavily in [[howitzer]]s and [[machine gun]]s. The British lacked an official tactical doctrine, with an officer corps that rejected theory in favour of pragmatism.{{sfn|Bidwell|Graham|2004|pp=14–19}}

While the armies expected to use entrenchments and cover, they did not allow for the effect of [[Defence in depth|defences in depth]]. They required a deliberate approach to seizing positions from which fire support could be given for the next phase of the attack, rather than a rapid move to break the enemy's line.{{sfn|Bidwell|Graham|2004|p=27}} It was assumed that artillery could still destroy entrenched troops, or at least suppress them sufficiently for friendly infantry and cavalry to manoeuvre.{{sfn|Bidwell|Graham|2004|pp=24–25}}

[[File:French trench battle.jpg|thumb|French trench in northeastern France]]

Digging-in when defending a position was a standard practice by the start of WWI. To [[frontal assault|attack frontally]] was to court crippling losses, so an outflanking operation was the preferred method of attack against an entrenched enemy. After the [[First Battle of the Aisne|Battle of the Aisne]] in September 1914, an extended series of attempted flanking moves, and matching extensions to the fortified defensive lines, developed into the "[[Race to the Sea|race to the sea]]", by the end of which German and Allied armies had produced a matched pair of trench lines from the [[Switzerland|Swiss]] border in the south to the [[North Sea]] coast of Belgium.

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.{{sfn|Ellis|1977|p=4}} After the buildup of forces in 1915, the Western Front became a stalemated struggle between equals, to be decided by attrition. Frontal assaults, and their associated casualties, became inevitable because the continuous trench lines had no open flanks. Casualties of the defenders matched those of the attackers, as vast reserves were expended in costly counter-attacks or exposed to the attacker's massed artillery. There were periods in which rigid trench warfare broke down, such as during the [[Battle of the Somme]], but the lines never moved very far. The war would be won by the side that was able to commit the last reserves to the Western Front. Trench warfare prevailed on the Western Front until the Germans launched their [[Operation Michael|Spring Offensive]] on 21 March 1918.{{sfn|Bidwell|Graham|2004|pp=–25}} Trench warfare also took place on other [[Front (military)|front]]s, including in [[Italian Campaign (World War I)|Italy]] and at [[Gallipoli Campaign|Gallipoli]].

Armies were also limited by logistics. The heavy use of artillery meant that ammunition expenditure was far higher in WWI than in any previous conflict. Horses and carts were insufficient for transporting large quantities over long distances, so armies had trouble moving far from railheads. This greatly slowed advances, making it impossible for either side to achieve a breakthrough that would change the war. This situation would only be altered in WWII with greater use of motorized vehicles.<ref>Van Creveld, p. 109-41</ref><ref>{{cite web
 | url =https://www.iwm.org.uk/history/transport-and-supply-during-the-first-world-war
 | title =Transport and Supply During the First World War
 | website =Imperial War Museum
 | access-date =10 September 2021
 | quote =The adequacy of transport and supply networks played a major role in shaping strategies for operations throughout the First World War and in influencing their success or failure. }}</ref>