Trench warfare

• 1. Introduction

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  Trench warfare turned the ground itself into a weapon. A defender crouched in a ditch, shielded from small arms and substantially sheltered from artillery, could kill several approaching men before they ever reached him. That single fact bent the whole shape of the First World War. When the Race to the Sea began in September 1914, trench use spread rapidly along the Western Front. By the end of October that year, the front in Belgium and France had hardened into facing lines that lasted nearly until the war ended. The cause was a mismatch. Firepower had undergone a revolution. Mobility had not. So the defender held the advantage, and the result was grueling. How deep did these systems run, and what did men have to do to live in them? Why did attacks succeed and still cost severe casualties? And what finally let armies break a stalemate so total that its very name became a byword for futility?

• 2. Older Than World War I

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  Roman legions entrenched their camps nightly when on the move in the presence of an enemy. Long before machine guns, field works existed for as long as there had been armies. The general Belisarius had his soldiers dig a trench during the Battle of Dara in 530 AD. The siege known as the Battle of the Trench, in 627 AD, took its name from a defensive ditch dug to protect Medina. The architect of that plan was Salman the Persian, who suggested the trench. In the mid-18th century, Dahomey used trenches against Oyo attacks, placing one force to face the trench and another on the flank, with the flanking squad striking and then withdrawing to the trenches. During the New Zealand Wars, the Maori built trench and bunker systems inside fortified areas called pa. One British observer described loose bunches of flax covering the fence, against which bullets fell and dropped, with defenders repairing every hole made by the guns at night. In the 1980s, historian James Belich claimed the Maori had effectively invented trench warfare in the first stages of those wars, a claim others called baseless revisionism. The American Civil War saw extensive systems, most notably in the sieges of Vicksburg in 1863 and Petersburg in 1864-1865. At Petersburg, the Union army first used the rapid-fire Gatling gun, an important precursor to the machine gun that would soon define a far larger war.

• 3. The Stalemate Sets In

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  By 1914, technology had dramatically changed warfare, but the major armies had not fully absorbed what that meant. As the range and rate of fire of rifled small arms grew, attacking across open ground turned lethal, and rapid-firing artillery like the French 75 made it worse. The French and the Imperial German Army chose different paths. The French relied on speed and surprise in a doctrine called Attaque a outrance. The Germans relied on firepower, investing heavily in howitzers and machine guns. The British had no official tactical doctrine, with an officer corps that preferred pragmatism over theory. After the Battle of the Aisne in September 1914, a series of attempted flanking moves and matching extensions of the lines became the Race to the Sea. By its end, German and Allied armies had built a matched pair of trenches running from the Swiss border to the North Sea coast of Belgium. With continuous lines and no open flanks, frontal assaults and their casualties became inevitable. After the buildup of 1915, the Western Front settled into a struggle between equals to be decided by attrition. Logistics deepened the deadlock. Heavy artillery use pushed ammunition expenditure far above any previous conflict, and horses and carts could not move enough of it far from the railheads. That kept either side from achieving a breakthrough, a limit that would only change in the next war with motorized vehicles.

• 4. Building The Underground

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  A well-developed trench had to be at least 2.5 meters deep so men could walk upright and stay protected. The earliest trenches of 1914 were simple, lacking traverses, and pre-war doctrine packed men into them shoulder to shoulder, which brought heavy casualties from artillery. There were three standard ways to dig. Entrenching meant standing on the surface and digging down, the most efficient method since a large party could work the full length at once, though it left diggers exposed and could only be done out of sight or at night. Sapping extended a trench by cutting away at the end face, hiding the diggers but limiting the work to one or two men. Tunnelling was like sapping, but a roof of soil stayed in place until the trench was ready to occupy. British guidelines stated it would take 450 men six hours at night to complete 250 meters of front-line trench system. A specialized unit called trenchmen handled fast digging and repair, working in groups of four with an escort of two armed soldiers and carrying a 1911 semi-automatic pistol. They could do in three to six hours what regular infantry would take about two days to finish. Fellow soldiers looked down on them and called them cowards, because they were instructed to abandon the post and flee if attacked while digging. They were ordered to do so because only around 1,100 trained trenchmen existed in the whole war, and officers high on the chain of command valued them greatly.

• 5. Anatomy Of A Trench

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  The parapet was the banked earth on the lip facing the enemy, fitted with a fire step. The rear lip, called the parados, protected a soldier's back from shells falling behind the line. Sides were often revetted with sandbags, wire mesh, and wooden frames, and the floor was covered with wooden duckboards, sometimes raised to leave a drainage channel below. Trenches were never straight. They were dug in a zigzag or stepped pattern, with straight sections generally kept under ten yards, later broken into distinct fire bays joined by traverses. This meant the whole trench could not be enfiladed if the enemy got in at one point, and a grenade or shell blast could not travel far. British defensive doctrine early in the war called for three parallel lines linked by communications trenches. The front trench was lightly held and occupied in force mainly during stand to at dawn and dusk. Between 70 and 100 yards behind it sat the support trench, and between 100 and 300 yards further back lay the reserve trench, where troops massed for a counter-attack. German dugouts went much deeper than the British 2.5 to 5 meter standard, often a minimum of 12 feet and sometimes three stories down, with concrete staircases. The Germans had based that knowledge on studies of the Russo-Japanese War, and they often prepared multiple redundant systems. On their Somme front in 1916 they held two complete trench systems a kilometer apart, with a third partly finished a kilometer behind, a duplication that made a decisive breakthrough virtually impossible.

• 6. The Killing Field Of Wire

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  Belts of barbed wire 15 meters deep or more could stall infantry crossing the battlefield. The point was not the cut from a barb but the entanglement, forcing a soldier to stop and methodically work the wire off, taking several seconds or longer. Placed where men were most exposed to massed fire bays and machine guns, that delay was deadly. The military theorist Liddell Hart identified barbed wire and the machine gun as the two elements that had to be broken to regain a mobile battlefield. Loose lines tangled better than tight ones, so coils were often only partially stretched out, called concertina wire. The screw picket, invented by the Germans and later adopted by the Allies, let wiring parties work at night more quietly than driving stakes. Methods to defeat wire stayed rudimentary. Prolonged bombardment could damage it but not reliably, and the first soldier reaching it might jump on top to depress it for those behind, taking himself out of action for each line. British and Commonwealth wire cutters were designed for thinner native wire and could not cope with the heavier gauge German product. The Bangalore torpedo was adopted by many armies and stayed in use past the end of the next world war.

• 7. Weapons For Close Quarters

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  The hand grenade became one of the primary infantry weapons of trench warfare. At the war's start the standard soldier carried a rifle and bayonet, with little else emphasized, but trench fighting changed that fast. A grenade let a man strike without exposing himself, needed no precise aim to kill or maim, and could reach enemies hiding below ground. The British had stopped using grenadiers in the 1870s and entered the war with virtually none, improvising bombs from whatever was at hand. By late 1915 the Mills bomb was in wide circulation, and by the war's end 75 million had been used. Because troops were poorly equipped for this fighting, early encounters saw improvised arms: short wooden clubs, metal maces, spears, hatchets, trench knives, and brass knuckles. The novel All Quiet on the Western Front records that many soldiers preferred a sharpened spade to the bayonet, which tended to get stuck in an opponent. The machine gun dominated even more. The Germans embraced it from the outset, and by 1914 carried six per battalion against the British two and the Russian eight. Field Marshal Sir Douglas Haig was quoted in 1915 saying the machine gun was much overrated and two per battalion was more than sufficient. Its defensive power showed on the first day of the Battle of the Somme, when 60,000 British soldiers became casualties, the great majority lost under withering machine gun fire. The Canadians made the best use of the weapon, pioneering area denial and indirect fire under Major General Raymond Brutinel, thickening the artillery barrage at Vimy Ridge by aiming machine guns to deliver plunging fire on the Germans.

• 8. Mining, Gas, And The Way Out

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  Gentlemen, we may not make history tomorrow, but we shall certainly change the geography. So General Plumer told his staff the evening before the Battle of Messines. At 3.10 in the morning on the 7th of June 1917, the British detonated a series of mines to launch that battle. The average held 21 tons of explosive, and the largest, 125 feet beneath Saint-Eloi, was twice that at 42 tons. Mining ran through the war. On the 1st of July 1916, the first day of the Somme, the British blew 19 mines, including the Y Sap and Lochnagar mines near La Boiselle, each holding 24 tons and throwing earth 4,000 feet into the air. Two undetonated mines near Messines were lost after the war; one blew during a thunderstorm in 1955, and the other remains in the ground. Poison gas was the other terror. Tear gas came first, used by the French in August 1914. Chlorine followed at the Second Battle of Ypres in April 1915, easy to detect by scent and sight. Phosgene, first used in December 1915, was 18 times more powerful than chlorine and far harder to detect. Mustard gas, introduced by Germany in July 1917, lingered on the surface, burned the skin and eyes, and sank into trenches because it was heavier than air, though only 2 percent of its casualties died. The deadlock finally broke through tactics and machines. The Germans, drawing on doctrine that stressed manoeuvre and force concentration, developed infiltration tactics from Captain Willy Rohr's 1915 experiments in the Vosges, training stormtroopers to bypass strongpoints and let junior officers act on their own initiative. The British and French turned to tanks, and firing ports were installed in the newly arrived Renault FT. The armies that learned to bypass static lines with armour and combined arms ended trench warfare's reign, and its undetonated mine still waiting in Belgian ground is a reminder of how literally these battles reshaped the earth.