No image symbolizes the First World War with a greater sense of somberness than the trenches. Between 1914 and 1918, an estimated four million soldiers died fighting on the Western Front. Until the war’s final year, the Entente and Central Powers were locked in a grinding stalemate fought between wide lines of opposing trenches. It was a type of warfare utterly alien to the commanders of the day who expected victory to follow a series of decisive battles. Instead, they were forced to confront the harsh realities of attritional warfare.
Pre-War Thinking
Expectations for how a major conflict in Europe would be fought before the outbreak of the First World War on July 28, 1914, were significantly off the mark. European generals generally expected to be fighting decisive battles of the sort described by military thinkers like Carl von Clausewitz in the previous century.
Although instances of trench warfare had occurred before the First World War, which placed a greater emphasis on wearing down the enemy by gradually inflicting casualties and other material losses, most senior military officials envisioned a version of maneuver warfare in which a number of decisive battles would decide the outcome of the conflict. The common refrain that the troops would be “home by Christmas” indicates that few foresaw the grinding war of attrition in the trenches that would come to characterize the First World War.
The Offense-Defense Balance
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Sign up to our Free Weekly NewsletterMost military thinkers also wrongly assumed that the offense-defense balance would favor the offense. The offense-defense balance simply refers to whether it is easier for military forces to capture or defend territory. In conflicts where offensive action is advantageous, mobility, surprise, and aggression tend to rule the day. When defense is superior, stalemates are more likely because it is difficult for both sides to capture enemy ground. When the scales tip towards defense, armies struggle to make decisive gains on the battlefield and must instead try to wear each other down through attrition.
As Ben Garfinkel and Alan Dafoe explain, “European powers’ failure to predict the grueling attrition warfare that would characterize much of the First World War is often attributed to their failure to recognize that new technologies, such as machine guns and barbed wire, had shifted the European offense-defense balance for conquest significantly toward defense.”
Political scientist Stephen Van Evera similarly points out that “despite the large and growing advantage which defenders gained against attackers as a result of the invention of rifled and repeating small arms, the machine gun, barbed wire, and the development of railroads, Europeans increasingly believed that attackers would hold the advantage on the battlefield.”
1914: Not Home by Christmas
Following what Van Evera calls “the Cult of the Offensive,” the belligerents of the First World War made their opening moves by initiating a series of offensive campaigns. Germany, following the ideas of Alfred von Schlieffen, invaded Belgium and Luxembourg in an attempt to break through to Northern France. Meanwhile, the French gave up their fortified positions and attacked Germany in Alsace-Lorraine. Concurrently, Austria-Hungary first invaded Serbia but switched its focus to invading Poland and Russia, whereas Russia itself launched a two-pronged attack on Eastern Germany and Austrian Galicia.
Both the French and Germans had constructed trenches and field fortifications to pin enemy attackers down so they could shift their forces to the north, where they expected the pivotal fighting to occur.
Initially conceived as a temporary measure, the trenches proved difficult for attackers to overcome. Well-armed defenders were able to move their reserves up to points in the trench line when they were threatened, rendering it extremely tough for attackers to break through. Even when breakthroughs were achieved and a trench line was overwhelmed, a new one could be constructed relatively quickly, and any gains made by the attackers were marginal.
The result was that by the end of 1914, the armies of both the Entente and Central Powers were exhausted. The French had suffered over 950,000 casualties, and the Germans about 800,000. It was now becoming apparent that the course of this war had gone off script. Writing in his diary in September 1914, German Army officer Gerhard Tappen commented, “More and more, it appears that we have before us field fortifications across the entire front – a completely new form of warfare.”
1915: The Stalemate Endures
The Allies attempted to break through enemy lines with further offensives in 1915. General Joseph Joffre, Commander-in-Chief of French forces on the Western Front, together with the British, planned to launch simultaneous offensives at Artois and Champagne. The purpose of this two-pronged attack on two far-apart points on the front was to force the Germans to commit their reserves prematurely and overextend their lines, setting the stage for a successful Entente attack.
Meanwhile under General Erich von Falkenhayn, the Germans concocted their own strategy. In early March 1915, Falkenhayn approved his subordinate Hans von Seeckt’s plan to split the French and British forces by attacking the 25-kilometer front between Arras and Thiepval. However, by late April, the Russians now threatened the Austro-Hungarian position in the Carpathians to such a degree that the Falkenhayn was forced to send the 11th Army—which would have carried out Seeckt’s plan—to the Eastern Front, and the offensive was canceled.
The year ended with an enduring stalemate. The Entente offensives at Artois and Champagne had failed to make significant gains and the lines remained largely static. Commanders on both sides had recognized the difficulty of overcoming enemy defenses but remained committed to offensive actions, albeit with an added attritional phase typically carried out by a heavy preliminary bombardment.
1916: War by Attrition
By 1916, senior officers on both sides were aware that inflicting attrition upon the enemy was essential for victory, but their plans for achieving this differed considerably. As Robert T. Foley explains, the French and British leaders “envisioned the attrition of the German Army coming through their own offensives,” whereas the Germans “saw the attrition of Entente forces as resulting from their attacking a German Army in strong defensive positions.”
With French forces severely battered, the British, who were previously junior partners in the alliance, now had more authority to make strategic-level decisions. Douglas Haig, the new British commander, believed that the enemy’s reserves had to be worn down before any decisive battle could take place. Haig and Joffre agreed that the British would carry out a preliminary offensive in Flanders in late June, followed by a joint main offensive at the Somme in July.
Falkenhayn also believed that wearing out the enemy through attrition was vital but went about achieving this differently. He planned to force the French to attack the German Army, where it was strongest, by threatening their position at Verdun. When the French counterattacked, Falkenhayn planned to pummel them with artillery and bog them down in German offensives. He hoped that heavy French losses and poor morale would force the French to negotiate and split the alliance.
Again, neither side achieved their objectives. Losses at the Somme were appalling, but the battle was inconclusive. British casualties were about 420,000, French at roughly 200,000, and German at approximately 440,000. Similarly, at Verdun, the Germans failed to take French positions and draw the enemy into their trap. As a result, German losses were almost as high as those endured by the French, and they failed to achieve an attritional advantage.
1917: A Breakthrough Remains Elusive
After sustaining heavy losses at Verdun and the Somme, the Germans now withdrew to a new defensive position known as the Hindenburg Line. Named after the new German commander, Field Marshal Paul von Hindenburg, who replaced Falkenhayn in August 1916, the new German defensive line was bolstered by more robust fortifications like concrete pillboxes and was much shorter, making it easier to defend.
The forces of the Entente tried and ultimately failed to break through this new German defensive line. The most significant clashes occurred during the Battle of Passchendaele (the Third Battle of Ypres) between July 31 and November 10, 1917, wherein anywhere between 240,000 and 448,614 casualties were sustained by the Entente and 217,000 to 400,000 suffered by Germany.
Despite enduring yet another year of stalemate, Entente troops were able to employ various innovations that hinted at a possible future breakthrough. One of the most important instances was the British combined arms operation during the Battle of Cambrai between November 20 and December 7. The British deployed a combination of artillery, aircraft, infantry, and tanks to surprise the Germans and managed to penetrate all three lines of the Hindenburg defenses. However, the British did not have enough reserves to capitalize on the attack’s success, and they were forced to retreat when the Germans counterattacked in late November.
Although the British were only able to retain a handful of the gains they made at Cambrai, the success of the initial attack was promising. The British had first used tanks in 1916, but this had been their first true outing, and they had done remarkably well. Moreover, Cambrai demonstrated that a combined-arms approach could be used to overcome a strong defensive position, hinting at possible breakthroughs to come.
1918: The Stalemate Ends
In 1918, the pace of the war changed dramatically with the return of mobility to the Western Front. The collapse of Tsarist Russia in November 1917 freed up large numbers of German troops that could be redeployed from the Eastern Front to face the British and French.
On March 21, the Germans initiated Operation Michael, a massive spring offensive with the goal of breaking through Entente lines and seizing the channel ports that supplied the British. If the Germans succeeded, the British would be cut off from their maritime lines of communication and forced to retreat. The British could not afford to lose maritime access and, therefore, more heavily fortified their northern positions, leaving the south more exposed.
The Germans bombarded Entente positions before stormtroopers assaulted the trenches. In some sectors—particularly the south—the British lacked sufficient reserves, and the Germans made significant gains of up to 19 kilometers (12 miles) in just a few days.
By April 5, the Germans had advanced by 64 kilometers (40 miles). However, they were exhausted from heavy fighting and lacked the manpower to sustain the offensive. French reinforcements arrived, and the Germans lost momentum.
On April 7, the Germans made another attempt with a scaled-down offensive to the south of Ypres. They successfully seized control of the Messines ridge and a significant portion of the Passchendaele salient. However, just like before, the German offensive eventually lost its momentum.
The “Hundred Days” & The End of the War
The Germans tried once more with a number of offensives, primarily against the French on the southern line between May and July, but the German army was exhausted, and morale was faltering. This gave the Entente an opportunity to take the initiative. Entente forces launched a successful counterattack at the Second Battle of Marne on July 18, overwhelming the German right flank.
During the subsequent Battle of Amiens in August, the Entente made significant gains and was able to advance 11 kilometers (7 miles) on the first day alone. General Henry Rawlinson’s British Fourth Army, supported by Australian and Canadian Corps, together with the French First Army, was able to implement the lessons learned in combined-arms tactics from the previous year to great effect. Rawlinson deployed a formidable force composed of more than 2,000 guns, 450 tanks, and 1,900 aircraft.
After the first day of the Entente offensive on August 8, the Germans had lost an estimated 30,000 men, with a further 13,000 having been taken prisoner and the loss of more than 300 guns. German General Erich Ludendorff lamented that it had been “the black day of the German Army,” and he and Kaiser Wilhelm II concluded that they could no longer win the war.
What followed was known as the “Hundred Days,” marked by a series of successful Entente offensives. Despite stiff resistance, the Germans were forced to concede defeat, and an armistice was signed on November 11, 1918. After years of grinding stalemate and attrition in the trenches, the war was finally over.