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Trench warfare is a form of war in which both opposing armies have static lines of fortifications dug into the ground facing each other.
Fortification is almost as old as warfare itself; however it was traditionally not possible to defend more than a short defensive line or an isolated strongpoint. The very long fortifications of the ancient world, such as the Great Wall of China or Hadrian's Wall, were exceptions to the general rule and were in any case not designed to prevent entry of enemy troops, but simply to make it difficult for the invader to mount a penetration in strength. The Great Wall of China, for example, was not intended to keep raiders out, merely to prevent them bringing their horses.
Although both the art of fortification and the art of weaponry advanced a great deal in the second half of the second millennium, the advent of the longbow, the muzzle-loading musket, and even of artillery did not substantially change the traditional rule that a fortification required a large body of troops to defend it. Small numbers of troops simply could not maintain a volume of fire sufficient to repel a determined attack.
With the development of improved firearm technology in the mid-19th century, the situation changed rapidly. When the American Civil War opened in 1861, it was fought with much the same weapons and much the same tactics that had been used in the Napoleonic wars and indeed for several centuries. By the time it drew to a bloody close in 1865, it had become a preview of the First World War: complete with trenches, machine guns, field fortifications, and massive casualties.
Two main factors were responsible for the change. First, the new breech-loading firearms—which were curiously ignored by both sides until mid-way through the conflict—made it possible for a small number of troops to maintain a heavy volume of fire. A handful of defenders sheltering in a trench or behind an improvised obstacle could hold off a large body of attackers indefinitely. Second came the machine gun, which multiplied the power of the defender still further and yet did little for an attacker (provided only that the defenders could take cover).
Two less-significant but still major factors played a part. One was the development of barbed wire, which in itself did little harm to anyone but—crucially—could slow the progress of an attacking force, and thus allow emplaced machinegunners and riflemen time to inflict unacceptable losses.
Finally, after the end of the American Civil War, came the invention of modern high-velocity breech-loading artillery. Artillery in one form or another had been a part of warfare since classical times, and from the rise of gunpowder until the development of trench warfare in the 1860s had been a major killing force. With the development of modern artillery by Krupp, however, artillery regained much of its former killing power (as was graphically demonstrated in the Franco-Prussian War of 1870 to 1871).
Trench warfare reached its height in World War I. German and Allied (mostly French and British) forces soon learned that with modern weapons even a shallow scrape in the soil could be defended by a handful of infantry. To attack frontally was to court crippling losses, so an outflanking operation was essential. After the Battle of the Aisne in September, 1914, an extended series of attempted outflankings, and matching extensions to the fortified defensive lines, soon saw the celebrated "race to the sea"—the German and Allied armies dug what was essentially a single pair of trenches from the Swiss border in the south to the North Sea coast of Belgium. Trench warfare prevailed on the Western Front from September 16, 1914 until the Germans launched their "Spring Offensive", Operation Michael, on March 21, 1918.
On the Western Front, the small, improvised trenches of the first few months rapidly grew deeper and more complex, gradually becoming vast areas of interlocking defensive works. The space between the opposing trenches was refered to as "no man's land" and varied in distance depending on the battlefield. On the Western Front it was typically between 100 and 300 yards, though only 30 yards on Vimy Ridge. After the German withdrawal to the Hindenburg line in March 1917 it stretched to over a kilometre in places. At the infamous "Quinn's Post" in the cramped confines of the Anzac battlefield at Gallipoli, the opposing trenches were only 15 metres apart and a bombing war was waged there incessantly. On the Eastern Front and in the Middle-East, the areas to be covered were so vast, and the distances from the factories that supplied shells, bullets, concrete and barbed wire so great, that trench warfare in the European style often did not eventuate.
Early in the war the British defensive doctrine suggested a main trench system of three parallel lines with each line connected by communications trenches. The point at which a communications trench intersected the front trench was of critical importance and was usually heavily fortified. The front trench was lightly garrisoned and typically only occupied in force during "stand to" at dawn and dusk. Between 70 and 100 yards behind the front trench was located the support (or "travel") trench to which the garrison would retreat when the front trench was bombarded. Between 300 and 500 yards further to the rear was located the third reserve trench where the reserve troops could amass for a counter-attack if the front trenches were captured. This defensive layout was soon rendered obsolete as the power of the artillery grew.
Temporary trenches were also built. When a major attack was planned, assembly trenches would be dug near the front trench. These were used to provide a sheltered place for the waves of attacking troops who would follow the first waves leaving from the front trench. "Saps" were temporary, unmanned, often dead-end, utility trenches dug out into no man's land. They fulfiled a variety of purposes such as connecting the front trench to a listening post close to the enemy wire or providing an advanced "jump off" line for a surprise attack.
Behind the front system of trenches there were usually at least two more partially prepared trench systems, kilometres to the rear, ready to be occupied in the event of a retreat. The Germans often prepared multiple redundant trench systems; in 1916 their Somme front featured two complete trench systems, one kilometre apart, with a third partially complete system a further kilometre behind. This duplication made a decisive break-through virtually impossible. In the event that a section of the first trench system was captured, a "switch" trench would be dug to connect the second trench system to the still-held section of the first.
The Germans made something of a science out of designing and constructing defensive works. They used reinforced concrete to construct deep, shell-proof, ventilated dugouts as well as strategic strongpoints. They were more willing than their opponents to make a strategic withdrawal to a superior, prepared defensive position. They were also the first to apply the concept "defence in depth" where the front line zone was hundreds of yards deep and contained a series of redoubts rather than a continuous trench. Each redoubt could provide supporting fire to its neighbours and while the attackers had freedom of movement between the redoubts they would be subjected to withering enfilade fire. The British eventually adopted a similar approach but it was incompletely implemented when the Germans launched the 1918 "Spring Offensive" and proved disastrously ineffective.
Trenches were never straight but were dug in a square-toothed pattern that broke the line into bays connected by traverses. This meant that a soldier could never see more than 10 metres or so along the trench, consequently the entire trench could not be enfiladed if the enemy gained access at one point or if a bomb or shell landed in the trench, the shrapnel could not travel far. The side of the trench facing the enemy was called the "parapet" and had a "fire step". The rear of the trench was called the "parados". The "parados" protected the soldier's back from shrapnel from shells falling behind the trench. If the enemy captured the trench then the "parados" would become their "parapet". The sides of the trench were revetted with sandbags, wooden frames and wire mesh. The floor of the trench was usually covered by wooden "duckboards". Dugouts of varying degrees of luxury would be built in the rear of the support trench.
The guidelines for British trench construction stated that it would take 450 men 6 hours (at night) to complete 250 metres of a front line trench system. Thereafter the trench would require constant maintenance to prevent deterioration caused by weather or shelling.
The battlefield of Flanders, which saw some of the worst fighting, presented numerous problems for the practice of trench warfare, especially for the British who were often compelled to occupy the low ground. In most places, the water table was only a metre or so below the surface so that any trench dug in the ground would quickly flood, consequently many "trenches" in Flanders were actually above ground and contructed from massive breastworks of sandbags (actually filled with clay). Initially both the parapet and parados of the trench were built in this way but a later technique was to dispense with the parados for much of the trench line, thus exposing the rear of the trench to fire from the reserve line in case the front was breached.
An individual soldier's time in the front line trench was usually brief; from as little as one day to as much as two weeks at a time before being relieved. The Australian 31st (Queensland) Battalion once spent 53 days in the line at Villers Bretonneux but such a duration was a rare exception. A typical British soldier's year could be divided as follows:
Some sectors of the front saw little activity throughout the war, making life in the trenches comparatively easy. When the I Anzac Corps first arrived in France in April, 1916, after the evacuation of Gallipoli, they were sent to a relatively peaceful sector south of Armentières to "acclimatise". Other sectors were in a perpetual state of violent activity. On the Western Front, Ypres was invariably hellish, especially for the British in the exposed, overlooked salient. However, quiet sectors still amassed daily casualties through sniper fire, artillery and gas. In the first six months of 1916, before the launch of the Somme Offensive, the British did not engage in any significant battles on their sector of the Western Front and yet suffered 107,776 casualties.
A sector of the front would be allocated to an army corps, usually containing three divisionss. Of these two would occupy adjacent sections of the front and the third would be in rest to the rear. This break down of duty would continue down through the army structure so that within each front line division, typically containing three infantry brigades, two brigades would occupy the front and the third would be in reserve. Within each front line brigade, typically containing four battalions (regiments for the Germans), two battalions would occupy the front with two in reserve. An so on for companies and platoons. The lower down the structure this division of duty proceeded, the more frequently the units would rotate from front line duty to support or reserve.
During the day, snipers and artillery observers in balloons made movement perilous so the trenches were mostly quiet. Consequently, the trenches were busiest at night when cover of darkness allowed the movement of troops and supplies, the maintenance and expansion of the barbed wire and trench system, and reconnaissance of the enemy's defences. "Saps" (shallow, dead-end trenches) were driven into no man's land and would have a listening post at the end where sentries would try and detect enemy patrols or working parties.
Raids were carried out to try and capture prisoners and "booty" — letters and other documents that provide intelligence about the unit occupying the opposing trenches. As the war progressed, raiding became part of the general British policy, the intention being to maintain the fighting spirit of the troops and to deny no man's land from the Germans. Such dominance was achieved at a high cost and a post-war British analysis concluded that the benefits were probably not worth the price.
Early in the war, surprise raids would be mounted, particularly by the Canadianss, but increased vigilance made achieving surprise difficult as the war progressed. By 1916, raids were carefully planned exercises in combined arms and involved close cooperation of infantry and artillery. A raid would begin with an intense artillery bombardment designed to drive off or kill the front trench garrison and cut the barbed wire. Then the bombardment would shift to form a "box", or cordon, around a section of the front line to prevent a counter-attack intercepting the raid.
The common infantry soldier had three weapons at his disposal in the trenches; the rifle, bayonet and grenade.
The standard British rifle was the .303 Short Magazine Lee-Enfield which was originally developed as a cavalry carbine and had an effective range of 1400 yards though in the hands of the average soldier, 200 yards was about the limit of accurate fire. British infantry training emphasised rapid fire rifle shooting rather than accuracy. Early in the war the British were able to defeat German attacks at Mons and the First Battle of Ypres using massed rifle fire but as trench warfare developed the opportunities to assemble a line of riflemen became rare.
The British soldier was equipped with a 21-inch sword bayonet which was too long and unwieldly to be particularly effective in close quarters combat.
The grenade came to be the primary infantry weapon of trench warfare. Both sides were quick to raise specialist bombing squads. The grenade enabled a soldier to engage the enemy indirectly (without exposing himself to fire) and it did not require the precise accuracy of rifle fire in order to kill or maim. The Germans and Turks were well equipped with grenades from the start of the war but the British, who had ceased using grenadiers in the 1870s, entered the war with virtually none such that soldiers had to improvise bombs with whatever was available. By late 1915 the British Mills bomb had entered wide circulation and by the end of the war 75 million of them had been used.
The machine gun is perhaps the signature weapon of trench warfare with the image of ranks of advancing infantry being scythed down by the withering hail of bullets. The Germans embraced the machine gun from the outset -- in 1904 every regiment was equipped with one machine gun -- and the machine gun crews were the elite infantry units. At Gallipoli and in Palestine the Turks provided the infantry but it was usually Germans who manned the machine guns.
The British high command were less enthusiastic about machine gun technology, considering the weapon "unsporting", and they always lagged behind the Germans in adopting the weapon. However, by 1917 every company in the British forces was equipped with four Lewis guns which significantly enhanced their firepower.
The heavy machine gun was a specialist weapon and in a static trench system was employed in a scientific manner with carefully calculated fields of fire so that at a moments notice an accurate burst could be laid upon the enemy's parapet or at a break in the wire. The British water-cooled Vickers machine gun required a 16 man crew and cost 30£ a minute to operate. Each belt of ammunition had to be hand loaded with 250 rounds and the barrel of the gun had to be changed after two belts were fired. It was a fragile and difficult weapon to maintain and operate but was very effective.
Mortarss, which lobbed a shell a relatively short distance, were widely used in trench fighting for harassing the forward trenches and for cutting wire in preparation for a raid or attack. In 1914 the British fired a total of 545 mortar shells. In 1916 they fired over 6,500,000 shells.
The main British mortar was the Stokes mortar which was the precursor of the modern mortar. It was a light mortar but was easy to use and capable of a rapid rate of fire by virtue of the propellant cartridge being attached to the shell. To fire the Stokes mortar, the round was simply dropped into the tube where the cartridge was ignited when it struck the firing pin at the bottom.
The Germans used a range of mortars. The smallest were grenade-throwers
(granatenwerfer) which fired "pineapple" bombs. Their medium trench-mortars were called mine-throwers (minenwerfer), dubbed "minnies" by the British. The heavy mortar was called the ladungswerfer which threw "aerial torpedoes", containing a 200 lb charge, over 1000 yards. The flight of the missile was so slow and leisurely that the men on the receiving end could make some attempt to seek shelter.
Artillery dominated the battlefield of trench warfare in the same way the air power dominates the modern battlefield. An infantry attack was rarely successful if it advanced beyond the range of its supporting artillery. In addition to bombarding the enemy infantry in the trenches, the artillery would engage in counter-battery duels to try and destroy the enemy's guns.
Three quarters of the wounds inflicted during the war came from shell fire. The wound resulting from a shell fragment was usually more traumatic than a gunshot wound. A shell fragment would often introduce debris making it more likely that the wound would become infected. These factors meant that a soldier was three times more likely to die from a shell wound to the chest than from a gunshot wound. The blast from shell explosions could also kill by concussion. In addition to the physical effects of shell fire there was the psychological damage. Men who had to endure a prolonged bombardment would often suffer debilitating shell shock, a condition that was not well understood at the time.
Artillery pieces were of two types; guns and howitzers. Guns fired high velocity shells over a flat trajectory and were often used to deliver
shrapnel and to cut barbed wire. Howitzers lofted the shell over a high
trajectory such that it plunged into the ground. The biggest artillery
were usually howitzers. The German 420 howitzer weighed 20 tons and could
fire a one ton shell over six miles.
Germany was the main innovator of gas warfare. Tear gas was first employed in January 1915 but this could only disable the enemy. In April 1915, chlorine was first used. A large enough dose could kill but the gas was easy to detect by scent and sight. Those that were not killed on exposure could suffer permanent lung damage.
Phosgene was the ultimate killing gas of World War I -- it was 18 times more powerful than chlorine and much more difficult to detect. However, the most effective gas was mustard gas. Mustard gas was not as fatal but it was hard to detect and lingered on the surface of the battlefield and so could inflict casualties over a long period. The burns it produced were horrific such that a casualty resulting from mustard gas exposure was unlikely to be fit to fight again. Only 2% of mustard gas casualties died, mainly from secondary infections.
The first method of employing gas was by releasing it from a cylinder when the wind was favourable. Such an approach was obviously prone to miscarry if the direction of the wind was misjudged. Also the cylinders needed to be positioned in the front trenches where they were liable to be ruptured during a bombardment. Later in the war, gas was delivered by artillery or mortar shell.
The Germans employed flame throwers (flammenwerfer) during the war but the technology was not mature so they were more effective at inducing terror than inflicting casualties.
In the Anzac trenches at Gallipoli, where the Turks held the high ground, the periscope rifle was developed to enable the Australians and New Zealanders to snipe at the enemy without exposing themselves over the parapet.
All sides would engage in vigorous mining and counter-mining duels. The dry chalk of the Somme was especially suited to mining but with the aid of pumps it was also possible to mine in the sodden clay of Flanders. Specialist tunnelling companies, usually made up of men who had been coal miners in civilian life, would dig tunnels under no man's land and beneath the enemy's trenches. These mines would then be packed with explosives and detonated, producing a large crater. The crater served two purposes; it could destroy or breach the enemy's trench and, by virtue of the raised lip that they produced, could provide a ready-made "trench" closer to the enemy's line. When a mine was detonated, both sides would race to occupy and fortify the crater.
If the miners detected an enemy tunnel in progress, they would often drive a counter-tunnel, called a camouflet, which would be detonated in an attempt to destroy the other tunnel prematurely. Night raids were also conducted with the sole purpose of destroying the enemy's mine workings.
The British detonated a number of mines on July 1, 1916, the first day of the Battle of the Somme. The largest mines — the Y Sap Mine and the Lochnager Mine — each containing 24 tons of explosives, were blown near La Boiselle, throwing earth 4,000 feet into the air.
At 5.10 am on June 7, 1917, 19 mines were detonated by the British to launch the Battle of Messines. The average mine contained 21 tons of explosive and the largest, 125 feet beneath St. Eloi, was twice the average at 42 tons. The combined force of the explosions was supposedly felt in England. As the Chief of Staff of the British Second Army, General Sir Charles Harrington, commented on the eve of the battle:
Ever greater forces of artillery were massed to try to batter the opposing lines into submission. The main effect was to churn the ground up into vast seas of mud: organised tactical movement became almost impossible; any attempt to advance was slowed still further, troops in the open were exposed to fire for a longer time.
Enormous frontal attacks by thousands of infantrymen took place, backed by massive artillery barrages and poison gas. The territorial gains were trivial; the losses so heavy that both sides began to run out of troops to waste. For the Central Powers, ever-harsher conscription laws and an emphasis on at least a little economy of life was the response. The Allies poured in troops from Canada, Australia, New Zealand, South Africa, the French African colonies, and eventually the United States, always in the hope that, this time, a yet bigger attack with still more unarmoured troops and an even longer artillery barrage to precede it would finally achieve the chimerical goal of a general break-through.
From time to time, at a frightful cost in human life, attackers did indeed break through the opposing line. But in no case was it possible to exploit the break: it was always easier for the defender to bring up reserves and improvise another trench line than it was for the attacker to pass his own reserves through the broken ground and mud and chaos of the battlefield. In any case, attacking generals had no way of knowing that a breakthrough had in fact occurred until a messenger from the front could arrive, usually on foot. Field telephone wires rarely survived a defensive artillery barrage, and by the time new ones could be laid, the opportunity had passed.
The new tactic of trench warfare had come about as a response to the new technologies of rapid fire weapons and mass-produced barbed wire. In consequence it is often thought that the end of trench warfare was itself brought about by new technologies, in particular the tank. Tanks were certainly a significant factor, however until quite late in the war they were available in only small numbers, and were often mis-employed by generals who had (of course) not yet gained experience with them. Soon after the war, analysts on both sides were highly motivated to exaggerate the role of the tank in ending trench warfare. For the Germans, it provided a ready explanation for their loss of the war; for ambitious Allied soldiers keen to see a large and independent tank corps (notably J.F.C. Fuller), stressing the importance of the tank was a way to achieve political goals; and for analysts in general, the tank provided a ready technological explanation where none of the other contemporary changes in military hardware seemed to fit—aircraft, gas, vastly more powerful artillery, and improved communications could not easily be understood to have made the difference.
In fact, the tank was only a partial explanation for the demise of trench warfare. Many Allied victories from 1917 on were achieved without tanks, or with very few of them, and the Germans too made large gains in early 1918 despite having hardly any tanks at all. The key lesson—which German tacticians learned all too well, and taught to their Allied pupils in the Blitzkrieg of 1940—was not technological but tactical. The keys to breaking the stalemate of trench warfare were to achieve tactical surprise, to attack the weakest parts of an enemy's line and bypass his strongpoints, and to abandon the futile attempt to have a grand and detailed plan of operations and control it from afar, instead relying on small, autonomous combined arms groups of well-trained soldiers where the junior leaders on the spot could exercise initiative.
The tank made it more difficult to defend a trench line. Combined arms warfare, where infantry, light artillery, and (if possible) tanks and aircraft operated in close cooperation made trench warfare obsolete.Background
Development
Implementation
Defensive system
Trench construction
Life in the trenches
Even when in the front line, the typical soldier would only be called upon to engage in fighting a handful of times a year — making an attack, defending against an attack or participating in a raid. The frequency of combat would increase for the men of the "elite" fighting divisions — on the Allied side; the British regular divisions, the Canadian Corps, the French XX Corps and the Anzacs.Weapons of trench warfare
Infantry weapons
Machine guns
Mortars
Artillery
Gas
Other
Mining
The craters from these and many other mines on the Western Front are still visible today. Three further mines were laid for Messines but were not detonated as the tactical situation had since changed. One blew during a thunderstorm in 1955, the other two remain to this day.Trench battles
Obsolescence
