Trench warfare
Trench warfare is a type of land warfare using occupied lines largely comprising military trenches, in which combatants are well-protected from the enemy's small arms fire and are substantially sheltered from artillery. It became archetypically associated with World War I, when the Race to the Sea rapidly expanded trench use on the Western Front starting in September 1914.
Trench warfare proliferated when a revolution in firepower was not matched by similar advances in mobility, resulting in a grueling form of warfare in which the defender held the advantage. On the Western Front in 1914–1918, both sides constructed elaborate trench, underground, and dugout systems opposing each other along a front, protected from assault by barbed wire. The area between opposing trench lines was fully exposed to artillery fire from both sides. Attacks, even if successful, often sustained severe casualties.
The development of armoured warfare and combined arms tactics permitted static lines to be bypassed and defeated, leading to the decline of trench warfare after the war. Following World War I, "trench warfare" became a byword for stalemate, attrition, sieges, and futility in conflict.
Precursors
Field works have existed for as long as there have been armies. Roman legions, when in the presence of an enemy, entrenched camps nightly when on the move. The Roman general Belisarius had his soldiers dig a trench as part of the Battle of Dara in 530 AD.Trench warfare was also documented during the defence of Medina in a siege known as the Battle of the Trench. The architect of the plan was Salman the Persian who suggested digging a trench to defend Medina.
There are examples of trench digging as a defensive measure during the Middle Ages in Europe, such as during the Piedmontese Civil War, where it was documented that on the morning of May 12, 1640, the French soldiers, having already captured the left bank of the Po river and gaining control of the bridge connecting the two banks of the river, and wanting to advance to the Capuchin Monastery of the Monte, deciding that their position wasn't secure enough for their liking, then choose to advance on a double attack on the trenches, but were twice repelled. Eventually, on the third attempt, the French broke through and the defenders were forced to flee with the civilian population, seeking the sanctuary of the local Catholic church, the Santa Maria al Monte dei Cappuccini, in Turin, also known at that time as the Capuchin Monastery of the Monte.
In early modern warfare, troops used field works to block possible lines of advance. Examples include the Lines of Stollhofen, built at the start of the War of the Spanish Succession of 1702–1714, the Lines of Weissenburg built under the orders of the Duke of Villars in 1706, the Lines of Ne Plus Ultra during the winter of 1710–1711, and the Lines of Torres Vedras in 1809 and 1810.
file:Siege of Vicksburg 1863 10566.jpg|thumb|Trenches at the Siege of Vicksburg 1863
In the mid-18th century, Dahomey made use of trenches to defend against Oyo attacks. In one engagement against Oyo, Dahomey placed one corp to face the trench and another on the flank. While battling Oyo forces, the flanking squad launched attacks and withdrew to the trenches afterwards.
During the New Zealand Wars, the Māori utilized trench and bunker systems as part of fortified areas known as pā. According to one British observer, "the fence round the pa is covered between every paling with loose bunches of flax, against which the bullets fall and drop; in the night they repair every hole made by the guns". In the 1980s, historian James Belich claimed that the Māori had effectively invented trench warfare during the first stages of the New Zealand Wars, claims which have been as described as "baseless... revisionism". Some sources claim that Māori trenches influenced 20th-century trench warfare.
The Crimean War saw "massive trench works and trench warfare", even though "the modernity of the trench war was not immediately apparent to the contemporaries".
Union and Confederate armies employed field works and extensive trench systems in the American Civil War — most notably in the sieges of Vicksburg and Petersburg, the latter of which saw the first use by the Union army of the rapid-fire Gatling gun, the important precursor to modern-day machine guns. Trenches were also utilized in the Paraguayan War, the Second Anglo-Boer War, and the Russo-Japanese War.
Adoption
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 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 "French 75", machine gun and high explosive fragmentation rounds. The increases in firepower had outstripped the ability of infantry 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.The French and the Imperial German Army adopted different tactical doctrines: the French relied on the attack with speed and surprise and the Germans relied on firepower, investing heavily in howitzers and machine guns. The British lacked an official tactical doctrine, with an officer corps that rejected theory in favour of pragmatism.
While the armies expected to use entrenchments and cover, they did not allow for the effect of 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. It was assumed that artillery could still destroy entrenched troops, or at least suppress them sufficiently for friendly infantry and cavalry to manoeuvre.
Digging-in when defending a position was a standard practice by the start of WWI. To attack frontally was to court crippling losses, so an outflanking operation was the preferred method of attack against an entrenched enemy. After the 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", by the end of which German and Allied armies had produced a matched pair of trench lines from the 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. 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 Spring Offensive on 21 March 1918. Trench warfare also took place on other fronts, including in Italy and at 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.
Construction
Early World War I trenches were simple. They lacked traverses, and according to pre-war doctrine were to be packed with men fighting shoulder to shoulder. This doctrine led to heavy casualties from artillery fire. This vulnerability, and the length of the front to be defended, soon led to frontline trenches being held by fewer men. The defenders augmented the trenches themselves with barbed wire strung in front to impede movement; wiring parties went out every night to repair and improve these forward defences.The small, improvised trenches of the first few months grew deeper and more complex, gradually becoming vast areas of interlocking defensive works. They resisted both artillery bombardment and mass infantry assault. Shell-proof dugouts became a high priority.
File:Энякяинен 5.jpg|thumb|upright|A trench of the Änäkäinen fortification in Lieksa, Finland
A well-developed trench had to be at least deep to allow men to walk upright and still be protected.
There were three standard ways to dig a trench: entrenching, sapping, and tunneling. Entrenching, where a man would stand on the surface and dig downwards, was most efficient, as it allowed a large digging party to dig the full length of the trench simultaneously. However, entrenching left the diggers exposed above ground and hence could only be carried out when free of observation, such as in a rear area or at night. Sapping involved extending the trench by digging away at the end face. The diggers were not exposed, but only one or two men could work on the trench at a time. Tunnelling was like sapping except that a "roof" of soil was left in place while the trench line was established and then removed when the trench was ready to be occupied. The guidelines for British trench construction stated that it would take 450 men 6 hours at night to complete of front-line trench system. Thereafter, the trench would require constant maintenance to prevent deterioration caused by weather or shelling.
Trenchmen were a specialized unit of trench excavators and repairmen. They usually dug or repaired in groups of four with an escort of two armed soldiers. Trenchmen were armed with one 1911 semi-automatic pistol, and were only utilized when either a new trench needed to be dug or expanded quickly, or when a trench was destroyed by artillery fire. Trenchmen were trained to dig with incredible speed; in a dig of three to six hours they could accomplish what would take a normal group of frontline infantry soldiers around two days. Trenchmen were usually looked down upon by fellow soldiers because they did not fight. They were usually called cowards because if they were attacked while digging, they would abandon the post and flee to safety. They were instructed to do this though because through the war there were only around 1,100 trained trenchmen. They were highly valued only by officers higher on the chain of command.