Why Did They Dig Trenches in World War I?
The First World War transformed modern battle through the emergence of trench warfare, a defining characteristic that shaped the conflict from its start in 1914 to its end in 1918. This entrenchment was not a planned strategy, but rather a necessary adaptation to the brutal realities of modern warfare and the devastating effectiveness of modern weapons.
By the early 20th century, advances in weaponry meant that previous battlefield tactics had to be scrapped. Infantry could no longer march toward the enemy in formation, cavalry charges were impossible, making the grand maneuvers of past battles obsolete. The war soon became an effective stalemate at the front lines, most famously along the Western Front, with opposing armies digging into increasingly elaborate trench systems. Here’s a closer look at how trench warfare came to define World War I.
Protection From Artillery
Artillery was the most destructive weapon on the Western Front. Modern artillery shells could devastate troops in open terrain, raining down high-explosive shells, shrapnel, and poison gas. Artillery created zones in which almost nothing could survive in the open, putting an emphasis on defense and the advantage with the defender, as attacking became too risky.
Because of the catastrophic effects of artillery, generals were forced to dig in at the start of the war. Trenches were initially seen as a temporary measure, but they soon became an absolute necessity, providing crucial protection against shell fragments and shock waves from explosions. As artillery quickly became the war’s deadliest weapon — around 60% of battlefield casualties were caused by exploding artillery shells — the depth and complexity of trench systems grew to match this horrific aerial threat.
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Defense Against Rifle Fire and Machine Guns
Rifles were by far the most commonly used weapon of World War I. These were sophisticated weapons, with a firing rate much greater than that of their 19th-century predecessors. The standard British rifle, the Short Magazine Lee Enfield (SMLE) Rifle Mk III, had a maximum range of 2,493 yards (with an effective killing range of 600 yards), and a well-trained infantryman could fire 15 aimed rounds a minute. This alone made advancing across No Man's Land — the area between the two opposing front lines of trenches — incredibly perilous, and anyone sticking their head above a trench was an instant target.
Then there were machine guns, which made traditional infantry attacks a near-impossible undertaking. The modern machine gun, invented in 1884 by Hiram Maxim, was used in battle in the late 19th century, in conflicts such as the Boer War and the Spanish American War. The weapon revolutionized battlefield dynamics, as a single machine gun could fire hundreds of rounds per minute, effectively defending against hundreds of attacking troops. Trenches provided essential cover from both rifle fire and the sustained attacks of machine guns, allowing soldiers to move and fight while staying below the enemy’s line of sight.
A Deep Defensive Strategy
As World War I progressed, trenches became far more than just ditches for duck-and-cover protection. They quickly formed part of a sophisticated defensive strategy (much like the layered battlements of a large medieval castle). On the Western Front, the line of trenches stretched from the North Sea all the way down to Switzerland — a distance of about 475 miles.
The classic British trench was about 6 feet deep and 3.5 feet wide, although deeper and more elaborate trenches were built. They were typically constructed in a zigzagging pattern, so that any enemies who managed to infiltrate the trench could not fire along its entire length, and blasts from exploding grenades and artillery shells couldn’t travel far along a single trench.
Behind the front line there could be three or four more lines of trenches, all connected by a system of communications trenches. If attackers captured the front line, they were then faced with additional entrenched positions that could be quickly reinforced. Support trenches housed reserves, supplies, and command posts, creating a defensive depth that meant any major enemy offensive required massive resources, and usually resulted in heavy casualties for minimal gains. These support trenches also allowed soldiers to be rotated in and out of the front line. A soldier might spend four to six days in the frontline trench before being sent to the support or reserve trenches further back for some much-needed rest and recuperation.
The End of Trench Warfare
The trench systems of World War I represented both the pinnacle and the end of static defensive warfare. While trenches were used in later conflicts, they never again dominated warfare as they did from 1914 to 1918.
The stalemate of trench warfare came to an end with the Battle of Amiens and the beginning of what came to be known as the Hundred Days Offensive, a string of Allied offensive successes on the Western Front that led to the collapse of the German army and the end of the war. At Amiens, the Allied forces launched the largest combined arms offensive of the entire war, with thousands of heavy and super-heavy field guns, more than 600 tanks, and 2,000 aircraft. They advanced some 8 miles in three days, along a 15-mile-wide front, a massive achievement in a war characterized by minute gains. The deadlock was broken, and the German trenches were ultimately overrun. In time the trenches dug during the war were reclaimed by nature, or filled in and returned to agricultural land, though unexploded ordnance remained a problem for many years. Others were preserved or turned into monuments, such as the trenches at Vimy near the Vimy Ridge Memorial in France, and Sanctuary Wood in Ypres, Belgium.
