World War I Summary

  • Last updated on November 11, 2022

World War I had its roots in several developments in the previous half century. Following the French defeat in the Franco-Prussian War (1870–1871) and the French loss of Alsace-Lorraine, Otto von Bismarck, the chancellor of the new German nation, sought to keep France isolated by constructing a complex series of alliances with the major powers. After Bismarck’s dismissal in 1890, the German Re-Insurance Treaty with Russia was not renewed. Within four years, Russia signed a military alliance with France. In 1904, France reached a treaty of friendship with England, and in 1907, Russia joined the agreement, forming the Triple Entente. Peacetime Europe became divided into two rival blocs: the Triple Entente and the Central Powers of Germany and Austro-Hungary.

World War I had its roots in several developments in the previous half century. Following the French defeat in the Franco-Prussian War (1870–1871) and the French loss of Alsace-Lorraine, Otto von Bismarck, the chancellor of the new German nation, sought to keep France isolated by constructing a complex series of alliances with the major powers. After Bismarck’s dismissal in 1890, the German Re-Insurance Treaty with Russia was not renewed. Within four years, Russia signed a military alliance with France. In 1904, France reached a treaty of friendship with England, and in 1907, Russia joined the agreement, forming the Triple Entente. Peacetime Europe became divided into two rival blocs: the Triple Entente and the Central Powers of Germany and Austro-Hungary.

T<sc>ime</sc> L<sc>ine of</sc> W<sc>orld</sc> W<sc>ar</sc> IJune 28, 1914Gavrilo Princip, a Serbian nationalist, assassinates Austria-Hungary’s Archduke Francis Ferdinand at Sarajevo.July 28Austria-Hungary declares war on Serbia; Russia mobilizes for war.August 1Germany declares war on Russia.August 3Germany declares war on France.Aug. 4, 1914Great Britain’s declaration of war on Germany.Aug. 14–25, 1914Battle of the Frontiers.Aug. 23, 1914Battle of Mons.Aug. 26–31, 1914Battle of Tannenberg.Sept. 5–9, 1914Battle of the Marne.Sept. 9–14, 1914Battle of Masurian Lakes.Oct. 30-Nov. 24, 1914First Battle of Ypres.Dec. 8. 1914Battle of Falkland Islands.Feb. 19, 1915-Jan. 9, 1916Gallipoli Campaign.Apr. 22-May 25, 1915Second Battle of Ypres.May 2-June 27, 1915Battle of Gorlice-Tarnow.June 23, 1915-Sept. 12, 1917Eleven Battles of the Isonzo.Dec. 8, 1915-Apr. 29, 1916Siege of Kut-al-Amara.Feb. 19-Dec. 18, 1916Battle of Verdun.May 31-June 1, 1916Battle of Jutland.June 4-Sept. 30, 1916Brusilov Offensive.June 24-Nov. 13, 1916Battle of the Somme.Mar. 11, 1917Battle of Baghdad.Apr. 6, 1917United States declares war on Germany.Apr. 9–15, 1917Battle of Vimy Ridge.June 15, 1917Espionage Act: United States Congress passes the Espionage Act. Implementation of this act leads to the suppression of free speech and the press during the war and to the prosecution and incarceration of political dissenters.July-Oct., 1917United States forces mass in eastern France. General John J. Pershing establishes headquarters in Chaumont.July 31-Nov. 10, 1917Third Battle of Ypres.Oct. 24-Nov. 12, 1917Battle of Caporetto.Oct. 31, 1917Battle of Beersheba.Nov. 20-Dec. 7, 1917Battle of Cambrai.Dec. 7, 1917United States declares war on Austria-Hungary.Apr. 6, 1918Piccardy Offensive: Germans attack Allied lines near Amiens.May 27-July 1, 1918Battle of Chateau-Thierry/Belleau Wood.July 8, 1917Mobilization: U.S. government organizes the War Industries Board to direct economic resources for the war effort.Aug. 8-Sept. 4, 1918Battle of Amiens.Sept. 12–16, 1918Battle of St. Mihiel: Offensive mounted almost totally by United States; ends German threat in the region and demonstrates U.S. military force.Sept. 20, 1918Battle of Megiddo.Sept. 26-Nov. 11, 1918Battle of Meuse-Argonne: U.S. offensive cuts off railroad supplies to Germans. Heavy casualties are suffered by the United States in this last significant battle of the war.Nov., 1918-Jan., 1923Postwar demobilization: Two million members of the American Expeditionary Force are reintegrated into the U.S. economy.Nov. 11, 1918Armistice ends the war.Jan. 18, 1919Peace conference opens in Paris.June 28, 1919Germany signs Treaty of Versailles.July 2, 1921Joint resolution of U.S. Congress recognizes a formal end to the war.
European Militarism and Nationalism

Militarism was also rampant in early twentieth century Europe. The French Schneider works and German Krupp works competed to produce more massive artillery and superior fortifications, and England and Germany were locked in a race to produce large numbers of state-of-the-art battleships (dreadnoughts). Both France and Germany instituted peacetime conscription laws to maintain large reserves of trained manpower.

Nationalism was flourishing in all major nations and the Balkans, where it resulted in two wars in 1912 and 1913. The fate of Bosnia-Herzegovina, taken over by the Austrian Empire in 1908 was particularly troublesome, setting off Serbian nationalism and angering Russia, which was the leader of Slavic nationalism. Disputes over imperialism, industrial competition between a rising Germany and a declining England, and the lack of an international body authorized to mediate national disputes were additional contributing factors.

Consequently, the assassination of Austria’s Archduke Francis Ferdinand in Sarajevo on June 28, 1914, by Bosnian nationalists allied to Serbia, set off a chain of events leading to the outbreak of war in early August. Encouraged by Germany, Austria-Hungary declared war on Serbia (July 28), and Russia mobilized, resulting in a German declaration of war on Russia (August 1). Germany then declared war on France (August 3). Under its Schlieffen Plan, Germany intended to invade Belgium in order to rapidly capture Paris and end the war.

Initially, most of the involved nations desired this war; however, none of them wanted it to last four years or be as destructive. All previous wars for the past century had been short and relatively bloodless. No nation had plans for fighting more than a three-month war, and all expected to return by Christmas with a short and decisive victory that would achieve their national objectives. In all European capitals, the war was greeted not with somberness but rather popular celebration. Men rapidly enlisted in order not to miss out on a short and glorious event.

Fighting Begins

Using precisely planned railroad timetables, in early August, 1914, Germany massed a five-front attack through Belgium in an effort to encircle Paris and bring France to its knees in the first months of the war. Belgian forts proved formidable. It took three weeks for Belgium to fall. The violation of Belgian neutrality brought England into the war on August 4. Germans met Anglo-French armies in a group of actions called the Battle of the Frontiers (August 14–25, 1914). France’s Plan Seventeen, which involved sending a highly motivated army to retake Alsace-Lorraine, failed miserably. French tactics did not take into account the dramatic changes that had taken place in the technology of killing since the Napoleonic era. At the Battle of Mons (August 23, 1914), outnumbered British forces battled the Germans but were forced to withdraw after French forces withdrew.

Allied offensives on the Western Front

The airplane, still in its infancy, was used in the first year of the war largely for observation of enemy movements. Eventually, pistols, rifles, and machine guns were brought along to drive off enemy planes. A major problem persisted in that airmen tended to shoot off their own propellers in the heat of combat. The Germans made the engineering breakthrough on their Fokker planes by developing a synchronized propeller with mounted machine guns. However, this technology was soon copied by the Allies.

The Russian offensive through East Prussia (August 17–20, 1914) was formidable. To meet the Russian advance, two corps from the western front, under generals Paul von Hindenburg and Erich Ludendorff were sent to revitalize the German Eighth Army in East Prussia. The Russian offensive was smashed in the Battle of Tannenberg (August 26–31, 1914) and Masurian Lakes (September 9–14, 1914). Russia’s poorly led and inadequately equipped forces suffered heavy casualties and lost more than one million soldiers as prisoners. As German troops were replaced by Austro-Hungarian forces, the eastern front of the war remained huge and fluid. Russian supply difficulties and the poor leadership of Generals Pavel Rennenkampf and Aleksandr Samsonov and Grand Duke Nicholas would be matched by Austro-Hungarian incompetence in fighting a modern war.

On the western front, German forces reached the Marne River, twenty miles outside of Paris. In a less than heroic stand, the French government fled southward to reestablish itself at Bordeaux. However, the French commander, General Joseph-Jacques Césaire Joffre, committed every available reserve and commandeered every wheeled vehicle, including bicycles, to rush troops to fight the Battle of the Marne (September 5–9, 1914). Blocked in their efforts to take Paris, the German army, led by Helmuth von Moltke, turned to the west, capturing the Belgian ports of Zeebrugge and Ostend. However, after heavy fighting in the First Battle of Ypres (October 18-November 30, 1914), the German advance was stopped.

Germany’s failure to produce a clear victory destined it to fight a two-front war of attrition. On the western front, both sides dug in until a system of trenches extended from the English Channel to the Swiss Alps. Any opportunity for flanking movements had disappeared. Trenches could be taken only by costly frontal assault across no-man’s-land. Because neither side had planned to fight more than a three-month war, common sense might have dictated a negotiated settlement of the deadlock. Instead, each side tried to improvise.

Naval Warfare

The Allies had command of the high seas during 1914, effectively cutting off Germany from trade and contact with its colonies. Germany’s main port in China, Qingdao (Tsingtao), was easily taken over by Japan after it joined the Allied side on August 23. Following the minor Battle of Falkland Islands (December 8, 1914), most of the German fleet remained in German ports. However, the submarine, an unexpectedly effective weapon that the German navy had only passing interest in before the war, began to take a heavy toll on Allied shipping beginning in 1915.

The crew of a German submarine posing on their vessel in 1916. The development of Germany’s submarine fleet revolutionized naval warfare. (Library of Congress)

By February, neutral nations such as the United States were warned that ships sailing to British ports risked attack. On May 17, 1915, the British passenger ship Lusitania was sunk off the coast of Ireland by a German U-boat, causing 1,201 casualties, including 139 Americans. The United States was so enraged that Germany suspended U-boat attacks on passenger ships and diverted much of its submarine fleet to the Mediterranean.

Although an initial Austro-German offensive in the Carpathians (January 23, 1915) was blunted within a month by a large Russian army, new German forces siphoned from the western front under General August von Mackensen drove Russian forces out of Poland by August, 1915. Austro-German forces successfully invaded Serbia in early fall, 1915, and were helped in their efforts by Bulgaria, a new entrant in the war. The Allies focused on the taking of the Gallipoli Peninsula (1915–1916) in an effort to capture the Gallipoli Straits.

The Ottoman Empire had joined the Central Powers on October 28, 1914, closing the Allied maritime route to Russia. To break this stranglehold, Winston S. Churchill, British first lord of the admiralty, envisioned a bold plan. An Anglo-French naval force would heavily shell Ottoman forts for almost a month (beginning February 19, 1915); shelling would be followed by the amphibious landing of large expeditionary forces intent on seizing control of the Dardanelles. Not taking into account the high cliffs on the shoreline or the spirited opposition of well-entrenched Turkish forces, Australian, New Zealand, and Canadian forces under General Ian Hamilton soon became pinned down on the Gallipoli Peninsula, while a second landing force suffered a similar fate at Sulva Bay. This disastrous campaign, which almost ended Churchill’s political career, resulted in 252,000 Allied casualties and the withdrawal of forces beginning on December 20, 1915. The withdrawal occurred exactly at the time the Turks were using the last of their munitions.

Clearly the war was not going well for the Allies, and a change in command was undertaken. Marshal Joffre was appointed commander of French forces and Field Marshal Douglas Haig was appointed British commander to replace John French. Another Christmas slipped by, and an end to the war was nowhere in sight.

New German Offensive

Early in 1916, Germany decided to break the stalemate by attacking the French fortress city of Verdun (February 19-December 18, 1916), a strategically central part of the French defensive system on the western front. While fortified positions changed hands many times during the lengthy battle, French forces under the command of Marshal Henri-Philippe Pétain ultimately prevailed, although France lost 315,000 men as compared with 281,000 German casualties. In order to take the pressure off Verdun, the Allies launched three attacks from June 24-November 13, 1916, collectively known as the Battle of the Somme. Anglo-French forces suffered 60,000 casualties on the first day of the offensive, which would stand as the bloodiest day in the war.

Much of the combat in the western front of the war was static, with armies mired in trenches, often suffering numerous casualties with little to show for their sacrifices. (U.S. Army War College)

Anglo-French forces made massive artillery barrages meant to destroy German barbed wire and machine-gun nests. However, neither objective was attained. By the end of the disastrous offensive, the Allies had lost nearly 800,000 men and the Germans 530,000. At the Somme, the tank was first used as a weapon of warfare in an attack near Courcelette (September 15, 1916) with inconsequential effect. In August, Ludendorff replaced Erich von Falkenhayn as Hindenburg’s chief of staff. Ludendorff was an advocate of total war, which meant military control at home, and striking decisive blows on the battle front.

Berated for not doing its share, Russian forces led by Aleksei Brusilov launched a campaign (June 4-September 30, 1916) known as the Brusilov Offensive into Galicia and the Carpathians. The attack wreaked havoc on poorly trained Austrian forces, which suffered 1.5 million dead, wounded, or captured to Russia’s comparatively smaller loss of 500,000. Romania entered the war on the Allied side during the attack, its appetite whetted by promises of territorial gains made in the secret Treaty of Bucharest (August 17). However, the Romanian push into Transylvania was halted. By December 6, much of Romania, including the capital city of Bucharest, was occupied by a German-Bulgarian army. Christmas, 1916, saw considerable disillusionment in soldiers on both fronts of the war.

Naval and Air Battles

The major naval battle of the war took place at Jutland (May-June, 1916) as twenty-eight British dreadnoughts and nine cruisers faced sixteen German dreadnoughts and five cruisers. The naval battle itself is viewed by most military historians to be a draw. However, the fact that the German fleet remained at port for the rest of the war makes the end result of the battle a British victory. Jutland also caused Germany to resume heavy reliance on its U-boats. In 1917, as Germany resumed unrestricted submarine warfare, Great Britain lost two million more tons of ships than were constructed, and the British Isles faced an acute food shortage.

Although the English experimented with squadron formations in 1916, air battles were usually duels between groups of planes, contests somewhat similar to the gallant jousting of knights of old. Heroes such as Baron Manfred von Richthofen, or the Red Baron, arose in this otherwise impersonal war. Bombing at first was merely tossing hand-held bombs from planes onto enemy troops below, but by 1917, wing-mounted bombs had been developed. Still, bombing played a very minor role in combat. The zeppelin, huge and slow, nevertheless became a terror weapon developed by the Germans. Zeppelins could deliver a large bomb payload, and attacks on England caused considerable panic among the population. However, zeppelins achieved their lift by using highly explosive hydrogen gas and were easy targets.

Allied Counteroffensives

Early in 1917, the new French commander, General Robert-Georges Nivelle attempted a breakthrough by launching a series of diversionary attacks at German positions along the Somme River and then launching a major offensive in Champagne (April 16, 1917). The offensive failed at the Second Battle of Aisne (May 9, 1917). Faced with mutinies by French troops during and after the battle, Nivelle was replaced by Marshal Pétain, who used courts-martial, firing squads, and other stringent measures to restore discipline.

Nivelle’s disaster was followed by an equally calamitous British effort by Haig to launch an offensive in Flanders (June 7, 1917) aimed at capturing the Flemish port cities of Ostend and Zeebrugge. The resulting Third Battle of Ypres (July 31-November 4, 1917) succeeded only in capturing Passchendaele Ridge. Both sides suffered heavy losses in this evident war of attrition and were bleeding each other dry. However, the Allies merely had to hold on, because a new and powerful nation was entering the war on their side.

United States Enters the War

The German resumption of unrestricted submarine warfare on February 1 angered the United States, led by President Woodrow Wilson, an Anglophile. Two days later, the United States terminated diplomatic relations with Germany and proceeded to pressure most of the major Latin American nations to do likewise. A miscalculated countermove to make the United States worry about events close at home resulted in the famous Zimmermann telegram (March 2) promising Mexico help, in the event of conflict, in regaining the American Southwest, lost in the Mexican War (1846–1848). This violation of the Monroe Doctrine, a sacred pillar of policy for the United States, was all that Wilson needed to move an isolationist nation to declare war on April 6. Since czarism had toppled in Russia several weeks earlier, to be replaced by the democratic provisional government, the United States could enter the war on the side of the democratic Allies against the autocratic central powers.

Wilson set the objective of the war as making the world safe for democracy, thus supplanting British prime minister David Lloyd George’s rationale that this was a war to end all wars. The initial American Expeditionary Force of 175,000, led by General John J. Pershing, arrived in France on June 25, greatly boosting French morale. By the end of the war, U.S. combat troops numbered two million and five million were in uniform. If the war of attrition were to continue, it was evident that Germany would atrophy first. However, other developments indicated that the war, in the short run, was turning in favor of Germany.

General John J. Pershing. (Library of Congress)

In order to knock Italy out of the war in one blow, Ludendorff sent seven well-trained German divisions, equipped with heavy artillery, to attack Italian forces at Caporetto (October 24-November 12, 1917) in Slovenia. One million Italian soldiers entered into a three-week-long retreat in which 350,000 were taken prisoner, and 40,000 were killed. German success against Italy was coupled with an even more spectacular event. In November, Vladimir Ilich Lenin, who had been smuggled by the Germans into Russia in a sealed train in early spring, had succeeded in seizing power in Russia. To maintain power, Lenin withdrew from the war. In the Treaty of Brest-Litovsk (1918), Lenin gave Germany control of nearly one-third of Russia’s most productive territory.

Other Theaters of the War

If things were going well for the Allies, it was in a secondary theater of the war, namely the Middle East. The British Mesopotamian campaign succeeded in capturing Baghdad on March 11, 1917, while General Lord Allenby took Jerusalem on December 9, after a victory at Beersheba on October 31. In Greece, an Allied invasion had convinced the pro-German King Constantine to abdicate in favor of his son Alexander (June 12). As planned, Alexander’s new premier, Venizelos, brought Greece into the war on the Allied side two weeks later.

With the end of the war on the Russian front, the Germans were able to reinforce their strength on the western front and plan a major offensive aimed at bringing the war to a decisive conclusion. The Ludendorff Offensive (1918) was intended to launch German divisions between French and English forces, enabling them to drive the English to the channel coast and then attack Paris. Beginning the offensive on March 21, four major attacks were made on Allied forces. The first attack, aimed at British forces south of Arras, hurled British lines back forty miles, before the front could be stabilized on April 5. In a second offensive at Lys (April 9–29, 1918), the Germans took Messines Ridge and Armentieres from the British.

A powerful attack on the Aisne (June, 1918) allowed German forces to drive to the Marne at a point thirty-seven miles from Paris. It was during this drive that U.S. forces played a significant role, halting the German advance at Château-Thierry/Belleau Wood (May 27-July 1, 1918). German forces were successfully able to cross the Marne in mid-July, but at this juncture Ferdinand Foch, who had been appointed Allied commander on April 24, ordered a counterattack, which began with a successful British attack on German forces at Amiens (August 8-September 4, 1918). Following German defeats at the Second Battle of the Somme, and the Fifth Battle of Arras, German forces were driven back to the Hindenburg Line (September 5). Allied forces also removed the Germans from the St. Mihiel salient (September 12–16, 1918).

U.S. troops fighting in France. (Library of Congress)

In September, the Americans launched the Meuse-Argonne Offensive (September 26-November 11, 1918), advancing through the Argonne Forest and breaking through German lines between Metz and Sedan. In October, the French took St. Quentin, and Britain occupied Cambrai and Ostend. By early November, the Hindenburg Line was broken, with German forces in full retreat. Austria-Hungary rapidly signed an armistice (November 3), joining Turkey, which had withdrawn from the war several days before, and Bulgaria, which had withdrawn from the war in late September.

Allied Victory

The defeat of the German army set off a naval mutiny, which in turn stimulated popular uprisings. Kaiser William II decided to leave Germany and seek refuge in the Netherlands. On November 9, 1918, Germany declared itself to be a democratic republic, hoping for a lenient peace treaty under Wilson’s Fourteen Points, the American president’s program for peace, which Wilson had laid out in a January, 1918, speech. At 5:00 a.m. on November 11, an armistice was signed. Six hours later, the guns were silent on the western front.

The armistice called for Germany’s surrender. Germany was to evacuate immediately all occupied territory and Alsace-Lorraine as well as German territory west of the Rhine and three bridgeheads over the Rhine. It was to surrender immediately a great deal of war equipment, including guns and machine guns, as well as its submarines.

The war broke up four empires: Austro-Hungarian, Ottoman, Russian, and German. It left nine million dead and seven million severely wounded. The Treaty of Versailles (June 28, 1919) imposed harsh conditions on Germany, including financial reparations based on its “war guilt,” or responsibility in starting the war, and considerable loss of territory. These conditions would play a part in the rise of the Nazis and the start of World War II.

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