brief summary world war 1

World War I Introduction and Overview

Belligerent nations.

• Origins of World War I

World War I on Land

World war i at sea, technical innovation, modern view.

• M.A., Medieval Studies, Sheffield University
• B.A., Medieval Studies, Sheffield University

World War I was a major conflict fought in Europe and around the world between July 28, 1914, and November 11, 1918. Nations from across all non-polar continents were involved , although Russia, Britain, France, Germany, and Austria-Hungary dominated. Much of the war was characterized by stagnant trench warfare and massive loss of life in failed attacks; over eight million people were killed in battle.

The war was fought by two main power blocks: the Entente Powers , or 'Allies,' comprised of Russia, France, Britain (and later the U.S.), and their allies on one side and the Central Powers of Germany, Austro-Hungary, Turkey, and their allies on the other. Italy later joined the Entente. Many other countries played smaller parts on both sides.

Origins of World War I

To understand the origins , it is important to understand how politics at the time. European politics in the early twentieth century were a dichotomy: many politicians thought war had been banished by progress while others, influenced partly by a fierce arms race, felt war was inevitable. In Germany, this belief went further: the war should happen sooner rather than later, while they still (as they believed) had an advantage over their perceived major enemy, Russia. As Russia and France were allied, Germany feared an attack from both sides. To mitigate this threat, the Germans developed the Schlieffen Plan , a swift looping attack on France designed to knock it out early, allowing for concentration on Russia.

Rising tensions culminated on June 28th, 1914 with the assassination of  Austro-Hungarian Archduke Franz Ferdinand  by a Serbian activist, an ally of Russia. Austro-Hungary asked for German support and was promised a 'blank cheque'; they declared war on Serbia on July 28th. What followed was a sort of domino effect as more and more nations joined the fight . Russia mobilized to support Serbia, so Germany declared war on Russia; France then declared war on Germany. As German troops swung through Belgium into France days later, Britain declared war on Germany too. Declarations continued until much of Europe was at war with each other. There was widespread public support.

After the swift German invasion of France was stopped at the Marne, 'the race to the sea' followed as each side tried to outflank each other ever closer to the English Channel. This left the entire Western Front divided by over 400 miles of trenches, around which the war stagnated. Despite massive battles like Ypres , little progress was made and a battle of attrition emerged, caused partly by German intentions to 'bleed the French dry' at Verdun and Britain's attempts on the Somme . There was more movement on the Eastern Front with some major victories, but there was nothing decisive and the war carried on with high casualties.

Attempts to find another route into their enemy’s territory led to the failed Allied invasion of Gallipoli, where Allied forces held a beachhead but were halted by fierce Turkish resistance. There was also conflict on the Italian front, the Balkans, the Middle East, and smaller struggles in colonial holdings where the warring powers bordered each other.

Although the build-up to war had included a naval arms race between Britain and Germany, the only large naval engagement of the conflict was the Battle of Jutland, where both sides claimed victory. Instead, the defining struggle involved submarines and the German decision to pursue Unrestricted Submarine Warfare (USW). This policy allowed submarines to attack any target they found, including those belonging to the 'neutral' United States, which caused the latter to enter the war in 1917 on behalf of the Allies, supplying much-needed manpower.

Despite Austria-Hungary becoming little more than a German satellite, the Eastern Front was the first to be resolved, the war causing massive political and military instability in Russia, leading to the Revolutions of 1917 , the emergence of socialist government and surrender on December 15. Efforts by the Germans to redirect manpower and take the offensive in the west failed and, on November 11, 1918 (at 11:00 am), faced with allied successes, massive disruption at home and the impending arrival of vast US manpower, Germany signed an Armistice, the last Central power to do so.

Each of the defeated nations signed a treaty with the Allies, most significantly the Treaty of Versailles which was signed with Germany, and which has been blamed for causing further disruption ever since. There was devastation across Europe: 59 million troops had been mobilized, over 8 million died and over 29 million were injured. Huge quantities of capital had been passed to the now emergent United States and the culture of every European nation was deeply affected and the struggle became known as The Great War or The War to End All Wars.

World War I was the first to make major use of machine guns, which soon showed their defensive qualities. It was also the first to see poison gas used on the battlefields, a weapon which both sides made use of, and the first to see tanks, which were initially developed by the allies and later used to great success. The use of aircraft evolved from simply reconnaissance to a whole new form of aerial warfare.

Thanks partly to a generation of war poets who recorded the horrors of the war and a generation of historians who castigated the Allied high command for their decisions and ‘waste of life’ (Allied soldiers being the 'Lions led by Donkeys'), the war was generally viewed as a pointless tragedy. However, later generations of historians have found mileage in revising this view. While the Donkeys have always been ripe for recalibration, and careers built on provocation have always found material (such as Niall Ferguson's The Pity of War ), the centenary commemorations found historiography split between a phalanx wishing to create a new martial pride and sideline the worst of the war to create an image of a conflict well worth fighting and then truly won by the allies, and those who wished to stress the alarming and pointless imperial game millions of people died for. The war remains highly controversial and as subject to attack and defense as the newspapers of the day.

• World War I Timeline: 1914, The War Begins
• 5 Key Causes of World War I
• World War I: A Stalemate Ensues
• World War I Timeline From 1914 to 1919
• The Fourteen Points of Woodrow Wilson's Plan for Peace
• The Causes and War Aims of World War One
• Causes of World War I and the Rise of Germany
• The Major Alliances of World War I
• Key Historical Figures of World War I
• The Countries Involved in World War I
• World War I: A Battle to the Death
• World War 1: A Short Timeline Pre-1914
• World War I: Opening Campaigns
• World War I: A Global Struggle
• The First Battle of the Marne
• World War 1: A Short Timeline 1915

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World War 1 Summary

Published: Mar 29, 2019 · Modified: Nov 7, 2023 by Russell Yost · This post may contain affiliate links ·

World War 1 was known as the Great War and was a global war that originated in Europe and would eventually consume many nations throughout the world. It lasted from July 29, 1914, to November 11, 1918, and led to more than 70 million military personnel being deployed throughout the world.

It was one of the largest wars in history and also one of the deadliest. Nine million combatants and seven million civilians died as a direct result of the war. Other genocides and the 1918 influenza pandemic caused at least 50 million more deaths.

The Dominoes Fall

The fighting.

On 28 June 1914, Gavrilo Princip, a Bosnian Serb Yugoslav nationalist,  assassinated the Austro-Hungarian heir Archduke Franz Ferdinand  in Sarajevo, leading to the July Crisis.

In response, on 23 July, Austria-Hungary issued an ultimatum to Serbia. Serbia's reply failed to satisfy the Austrians, and the two moved to a war footing.

While this may be one of the common beliefs for the cause of World War 1 , it is still debated.

Tensions had been rising throughout Europe with various arms races and alliances.

The great powers of Europe were divided into two coalitions:

Triple Entente: Consisted of France, Russia, and Britain

Triple Alliance: Germany, Austria-Hungary, and Italy.

These alliances caused a domino effect when Germany declared war on France and began to march through Belgium. Within weeks, the entire continent had declared war.

Germany fought the war on two fronts against France and Russia.

Their initial idea was to use the bulk of their army on the western front and defeat France in 4 weeks before Russia could mobilize. This plan would become known as the Schlieffen Plan.

An essential element of this plan was to gain free passage through Belgium to pounce on France quickly, but Belgium refused to give them passage, which Germany invaded.

The invasion set off a chain of events that led to France and Great Britain declaring war on Germany by August 4, 1914.

Eight days later, France and Britain declared war on Austria-Hungary.

August 23rd, Japan sided with the Entente and began seizing German possessions in China and the Pacific.

In November 1914, the Ottoman Empire entered the war on the side of the Alliance, which opened a front in the Caucasus, Mesopotamia, and the Sinai Peninsula.

European colonial empires also became vulnerable, which spread the conflict into the continent of Africa, the Indian Ocean, and across the globe.

The Entente and its allies would become known as the Allied powers, while Germany, Austria-Hungary, and their allies became known as the Central Powers.

The Kingdom of Bulgaria joined the Central Powers in 1915.

The Kingdom of Greece joined the Allied Powers in 1917.

3 years later, Germany attempted to incite Mexico to attack the United States. The attempt failed, and the United States would enter the war in 1917. This would become a major issue for the United States during the Election of 1916 and eventually the Election of 1920 .

Germany's advance was halted at the First Battle of the Marne , and by the end of 1914, the war became one of attrition. Long trench lines were created, and the battle lines did not change much until 1917.

Russia began to have internal problems. The February Revolution replaced the Tsarist autocracy with the Provisional Government. Discontent from the war grew and led to the October Revolution, which created the Soviet Socialist Republic. This caused Russia to exit World War 1.

This allowed the transfer of large numbers of German troops from the East to the Western Front, resulting in the German March 1918 Offensive

This offensive was initially successful, but the Allies rallied and drove the Germans back in their Hundred Days Offensive.

Bulgaria was the first Central Power to sign an armistice, the Armistice of Salonica, on September 29, 1918. On October 30, the Ottoman Empire capitulated, signing the Armistice of Mudros.

On 4 November, the Austro-Hungarian empire agreed to the Armistice of Villa Giusti.

With its allies defeated, the revolution at home, and the military no longer willing to fight, Kaiser Wilhelm abdicated on November 9, and Germany signed an armistice on November 11, 1918.

World War I was a significant turning point in the political, cultural, economic, and social climate of the world. The war and its immediate aftermath sparked numerous revolutions and uprisings.

The Big Four (Britain, France, the United States, and Italy) imposed their terms on the defeated powers in a series of treaties agreed at the 1919 Paris Peace Conference, the most well-known to be the German peace treaty, the Treaty of Versailles.

Related Article: World War 1 Timeline

What caused World War I and what were its effects?

Also called The Great War, World War I was one of the deadliest conflicts in history, and set the stage for another world war just 20 years later.

It was known as “ The Great War ”—a land, air and sea conflict so terrible, it left over 8 million military personnel and 6.6 million civilians dead . Nearly 60 percent of those who fought died. Even more went missing or were injured. In just four years between 1914 and 1918, World War I changed the face of modern warfare, becoming one of the deadliest conflicts in world history.

Causes of the Great War

World War I had a variety of causes, but its roots were in a complex web of alliances between European powers. At its core was mistrust between—and militarization in—the informal “ Triple Entente ” (Great Britain, France, and Russia) and the secret “ Triple Alliance ” (Germany, the Austro-Hungarian Empire, and Italy).

The most powerful players, Great Britain, Russia, and Germany, presided over worldwide colonial empires they wanted to expand and protect. Over the course of the 19th century, they consolidated their power and protected themselves by forging alliances with other European powers.

In July 1914, tensions between the Triple Entente (also known as the Allies) and the Triple Alliance (also known as the Central Powers) ignited with the assassination of Archduke Franz Ferdinand , heir to the throne of Austria-Hungary, by a Bosnian Serb nationalist during a visit to Sarajevo. Austria-Hungary blamed Serbia for the attack. Russia backed its ally, Serbia. When Austria-Serbia declared war on Serbia a month later, their allies jumped in and the continent was at war.

Archduke Franz Ferdinand (1863-1914), above, was assassinated in Sarajevo by a Serb nationalist. The event incident precipitated World War I.

The spread of war

Soon, the conflict had expanded to the world, affecting colonies and ally countries in Africa, Asia, the Middle East, and Australia. In 1917, the United States entered the war after a long period of non-intervention . By then, the main theater of the war—the Western Front in Luxembourg, the Netherlands, Belgium, and France—was the site of a deadly stalemate.

Despite advances like the use of poison gas and armored tanks, both sides were trapped in trench warfare that claimed enormous numbers of casualties . Battles like the Battle of Verdun and the First Battle of the Somme are among the deadliest in the history of human conflict.

Aided by the United States, the Allies finally broke through with the Hundred Days Offensive , leading to the military defeat of Germany. The war officially ended at 11:11 a.m. on November 11, 1918.

By then, the world was in the grips of an influenza pandemic that would infect a third of the global population. Revolution had broken out in Germany, Russia, and other countries. Much of Europe was in ruins. “Shell shock” and the aftereffects of gas poisoning would claim thousands more lives.

Never again?

Though the world vowed never to allow another war like it to happen, the roots of the next conflict were sown in the Treaty of Versailles , which was viewed by Germans as humiliating and punitive and which helped set the stage for the rise of fascism and World War II. The technology that the war had generated would be used in the next world war just two decades later.

Though it was described at the time as “the war to end all wars,” the scar that World War I left on the world was anything but temporary.

American Colonel Christopher Miller surveys the cratered landscape on the top of Fort de Vaux. The seemingly gentle hills are lasting testaments to the heavy shelling during the Battle of Verdun.

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World War I: ‘The War to End All Wars’

World war i facts.

The war fought between July 28, 1914, and November 11, 1918, was known at the time as the Great War, the War to End War, and (in the United States) the European War. Only when the world went to war again in the 1930s and ’40s did the earlier conflict become known as the First World War.

Its casualty totals were unprecedented, soaring into the millions. World War I is known for the extensive system of trenches from which men of both sides fought. Lethal new technologies were unleashed, and for the first time a major war was fought not only on land and on sea but below the sea and in the skies as well. The two sides were known as the Allies or Entente — consisting primarily of France, Great Britain, Italy, Russia, and later the United States — and the Central Powers, primarily comprised of Austria-Hungary (the Habsburg Empire), Germany, and the Ottoman Empire (Turkey). A number of smaller nations aligned themselves with one side or the other. In the Pacific Japan, seeing a chance to seize German colonies, threw in with the Allies. The Allies were the victors, as the entry of the United States into the war in 1917 added an additional weight of men and materiel the Central Powers could not hope to match.

WHEN DID WORLD WAR I START?

July 28, 1914

When Did World War I End?

November 11, 1918

WHERE DID WORLD WAR I TAKE PLACE?

Europe, Mediterranean, and Northern Africa

Who Won World War I?

The Allied powers, namely France, Great Britain, and the United States.

ALLIED Leaders

• Nicholas II, Czar of Russia
• Aristide Briand, Prime Minister of France (1915-1917)
• Georges Clemenceau, Prime Minister of France and Minister of War (1917–1920)
• H. H. Asquith, Prime Minister of the United Kingdom (1908–1916), Secretary of State for War (1914)
• David Lloyd George, Prime Minister of the United Kingdom (1916–1922), Secretary of State for War (1916)
• Woodrow Wilson, President of the United States

Central Power Leaders

• Franz Joseph I, Emperor of Austria (1848-1916)
• Karl I, Emperor of Austria (1916-1918)
• Wilhelm II, German Emperor
• Mehmed V, Sultan of the Ottoman Empire (1909-1918)

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World war i summary: .

The war resulted in a dramatically changed geopolitical landscape, including the destruction of three empires: Austro-Hungarian, Ottoman and Russian. New borders were drawn at its conclusion and resentments, especially on the part of Germany, left festering in Europe. Ironically, decisions made after the fighting ceased led the War to End War to be a significant cause of the Second World War.

As John Keegan wrote in  The First World War  (Alfred A. Knopf, 1999), “The First World War was a tragic and unnecessary conflict … the train of events that led to its outbreak might have been broken at any point during the five weeks of crisis that preceded the first clash of arms, had prudence or common goodwill found a voice.”

CASUALTIES IN WORLD WAR I

In terms of sheer numbers of lives lost or disrupted, the Great War was the most destructive war in history until it was overshadowed by its offspring, the Second World War: an estimated 10 million military deaths from all causes, plus 20 million more crippled or severely wounded. Estimates of civilian casualties are harder to make; they died from shells, bombs, disease, hunger, and accidents such as explosions in munitions factories; in some cases, they were executed as spies or as “object lessons.” Additionally, as Neil M. Heyman in  World War I  (Greenwood Press, 1997) wrote, “Not physically hurt but scarred nonetheless were 5 million widowed women, 9 million orphaned children, and 10 million individuals torn from their homes to become refugees.” None of this takes into account the deaths in the Russian Civil War or the Third Balkan War, both of which directly resulted from World War I, nor the Spanish influenza pandemic of 1918 that killed 50 million people worldwide, which was spread in part by conditions at the front and by soldiers returning home.

The highest national military casualty totals—killed, wounded, and missing/taken prisoner—in round numbers (sources disagree on casualty totals), were:

• Russia: 9,150,000
• Germany: 7,143,000
• Austria-Hungary: 7,000,000
• France, 6,161,000
• Britain & Commonwealth: 3,190,000
• Italy: 2,197,000
• Turkey (Ottoman Empire): 975,000
• Romania: 536,000
• Serbia: 331,000
• USA: 323,000
• Bulgaria: 267,000

For more information, click to see the  Casualties of World War I .

What Started World War I?

Prime Minister of Germany Otto von Bismarck had prophesied that when war again came to Europe it would be over “some damn foolish thing in the Balkans.” Indeed, the assassination of Archduke Franz Ferdinand, heir apparent to the Habsburg throne of Austria-Hungary, and his wife, Sophie, by a Serbian nationalist on June 28, 1914, was the match that lit the fuse—but it didn’t create the powder keg. The outbreak of war between European nations was the result of several factors:

• Concern over other countries’ military expansion, leading to an arms race and entangling alliances
• Fear of losing economic and/or diplomatic status
• Long-standing ethnic differences and rising nationalism in the Balkans
• French resentment of territorial losses in the 1871 Franco-Prussian War
• The influence exerted by military leaders

Following their 1871 victory in the Franco-Prussian War, the German states unified into a single nation. Its leader, Kaiser Wilhelm II, eldest grandson of Britain’s Queen Victoria, envisioned an Imperial Navy that could rival Great Britain’s large and renowned fleet. This would increase German influence in the world and likely allow the country to expand its colonial holdings. Britain, fearful of losing its dominance of the seas, accelerated its naval design and construction to stay ahead of the Kaiser’s ship-building program.

Russia was rebuilding and modernizing its large army and had begun a program of industrialization. Germany and Austria-Hungary saw the threat posed by Russia’s large population and, hence, its ability to raise a massive army. They formed an alliance for self-protection against the Russian bear.

France, still stinging over the loss of Alsace and part of Lorraine in the Franco-Prussian war, made an agreement allying itself with Russia in any war with Germany or Austria-Hungary. Britain, after finding itself friendless during the Second Boer War in South Africa (1899–1902) allied itself with France and worked to improve relations with the United States of America. Russia, with many ethnic groups inside its vast expanse, made an alliance with Serbia in the Balkans.

The old Ottoman Empire was crumbling; “The Sick Man of Europe” was the phrase used to describe the once-powerful state. As its ability to exert control over its holdings in the Balkans weakened, ethnic and regional groups broke away and formed new states. Rising nationalism led to the First and Second Balkan Wars, 1912 and 1913. As a result of those wars, Serbia increased its size and began pushing for a union of all South Slavic peoples. Serbian nationalism led 19-year-old Gavrilo Princip to assassinate Archduke Franz Ferdinand, heir apparent to the Habsburg throne of Austria-Hungary, and his wife, Sophie. Austria-Hungary, urged on by Germany, sent a list of demands to Serbia in response; the demands were such that Serbia was certain to reject them. When it did, the Habsburg Empire declared war on Serbia on July 28, exactly one month after the archduke’s assassination. Russia came in on the side of the Serbs, Germany on the side of the Habsburgs, and the entangling alliances between the nations of Europe pulled one after another into the war. Although diplomats throughout Europe strove to settle matters without warfare right up to the time the shooting started, the influence military leaders enjoyed in many nations won out—along with desires to capture new lands or reclaim old ones.

COMBAT IN THE FIRST WORLD WAR

German military planners were ready when the declarations of war began flying across Europe. They intended to hold off the Russians in the east, swiftly knock France out of the war through a maneuver known as the Schliefffen Plan, then throw their full force, along with Austria-Hungary, against the Russians. The Schliefffen Plan, named for General Count Alfred von Schlieffen who created it in 1905, called for invading the Low Countries (Luxembourg and Belgium) in order to bypass to the north the strong fortifications along the French border. After a rapid conquest of the Low Countries, the German advance would continue into northern France, swing around Paris to the west and capture the French capital. It almost worked, but German commander in chief General Helmuth von Moltke decided to send his forces east of Paris to engage and defeat the weakened French army head-on. In doing so he exposed his right flank to counterattack by the French and a British Expeditionary Force, resulting in the First Battle of the Marne, September 6–10, 1914. Despite casualties in the hundreds of thousands, the battle was a stalemate, but it stopped the German drive on Paris. Both sides began digging a network of trenches. The First Battle of the Marne was a window onto how the rest of the war would be fought: extensive trenchworks against which large numbers of men would be hurled, suffering extremely high casualties for little if any territorial gains. The centuries-old method of massed charges to break through enemy positions did not work when the men faced machine guns, barbed wire, and drastically more effective artillery than in the past.

The next four years would see battles in which millions of artillery shells were fired and millions of men were killed or mutilated. Click here to read about some of the  costliest battles of the First World War . Deadly new weapons were responsible for the unprecedented carnage.

NEW WEAPONS OF WORLD WAR I

Among the lethal technological developments that were used for the first time (or in some cases used for the first time in a major conflict) during the Great War were the machine gun, poison gas, flamethrowers, tanks and aircraft. Artillery increased dramatically in size, range and killing power compared to its 19th-century counterparts. In the war at sea, submarines could strike unseen from beneath the waves, using torpedoes to send combat and merchant ships to the bottom. Click here for more information on  Weapons of World War I .

WAR ON THE EASTERN FRONT

On the Eastern Front, the German general Paul von Hindenburg and his chief of staff Erich Ludendorff engineered strategies that gave them dramatic victories over Russian armies. The war became increasing unpopular among the Russian people. Ludendorff, sensing a chance to take Tsar Nicholas II’s country out of the war, arranged for an exiled Marxist revolutionary named Vladimir Lenin to cross Europe in a special train and get back into Russia. As hoped, Lenin helped fuel the rising revolutionary fervor. The tsar was deposed and executed with his family in the March 1917 revolution. For the first time in Russian history a republican democracy was established, but its leaders underestimated the people’s resistance to continuing the war. When the new government failed to bring about a rapid peace, it was overthrown in November by a socialist revolution led by Lenin, following which Russia signed a peace agreement with Germany.

WAR IN THE MOUNTAINS

Fighting in the high elevations of the Balkans and Alps created additional agony for soldiers fighting there: bitterly cold winters and especially rugged terrain.

Serbia, whose countryman had fired the shots that gave rise to the slaughter taking place in Europe, was invaded twice by Austria-Hungary but repulsed both attempts. In the autumn of 1915, a third invasion came. This time the Hapsburgs were joined by Germany and Bulgaria. The outnumbered Serbs gave ground. Ultimately, the Serbian Army only escaped annihilation by a demanding march through Albania to the Adriatic Sea, where the French Navy rescued the survivors.

Romania remained neutral until August 1916 when it joined the Allies and declared war on Austria-Hungary in hopes of securing additional territories including Transylvania. As the poorly trained Romanian army advanced into Transylvania, German forces invaded and occupied Romania itself, quickly knocking the country out of the war.

Italy, wooed by both sides, entered the war on the Allied side in May 1915. Its efforts were concentrated on breaking through Austria’s mountain defenses, but its poorly equipped soldiers were ground up in a series of attacks at the Isonzo River, though their opponents also suffered severely. What gains the Italians made in the war were wiped out by a rout that began at Caporeto in October 1917 and unhinged the entire line.

THE WAR SPREADS BEYOND EUROPE

While soldiers in Europe lived and died in the muddy, disease-ridden trenches, Britain attempted an attack in February 1915 against the Ottoman Empire, the “soft underbelly” of Europe, to aid the Russians and, ideally, force Turkey out of the war. An attempted invasion on the Gallipoli Peninsula resulted in a bloody repulse, but war in the interior of the Ottoman Empire met with greater success. Arab groups seeking to overthrow the empire waged a successful guerrilla war in the Mideast, led by Prince Feisal, third son of the Grand Sharif of Mecca. The revolt was aided by British liaison officer T.E. Lawrence of Wales, who became known as Lawrence of Arabia.

When the war ended, the Ottoman Empire was broken up. England and France drew borders for new countries in the Mideast without regard for ethnic and religious factions. The centuries-old tensions between the native inhabitants of the region led to many of the problems causing turmoil in the Mideast today, another irony of the War to End War.

Africa was home to a sideshow of the European fighting. European nationals and colonial troops of both sides fought against each other, but the German colonies were widely separated and unable to support each other. In German East Africa (Tanzania) an aggressive general named Paul von Lettow-Vorbeck waged a guerilla campaign against his British opponents until after the armistice was signed in Europe that ended the Great War.

In the waters of the Pacific Ocean German commerce raiders found prey among merchant vessels of Allied nations. Japan joined the Allies war effort on August 23, 1914, ostensibly in fulfillment of the Anglo-Japanese Treaty of 1911. The Land of the Rising Sun seized German colonies such as the Marianas, Marshalls and Carolines island chains that would see intense fighting during the Second World War.

Among the causes of the First World War was the naval arms race that began with Britain’s deployment of HMS  Dreadnought , a new design that eschewed small, secondary arms in favor of big guns heavily armored for protection. Every nation wanted a Dreadnought, and Germany sought to increase the size of its fleet to the level of Britain’s. Accomplishing that goal while supporting large armies engaged in warfare proved impossible for Germany, but World War I saw the last great battles fought entirely between surface ships. Notable naval engagements include the Falkland Islands and Coronel off South America, and the battles of Heligoland Bight, Dogger Bank and Jutland in the North Sea. Jutland would prove to be not only the largest naval battle up to that time but the last in which fighting would take place only between surface ships. In World War II, the aircraft carrier became the most lethal surface ship and allowed enemy fleets to engage in battle without ever seeing each other from a captain’s bridge.

The most significant advance in naval warfare to come out of the Great War was the development of submarines, which the German Imperial Navy called  Unterseeboots  (undersea boats). That got shortened to U-boats, a name that became synonymous with submarine. Subs could hide beneath the waves in shipping lanes to attack merchant or combat ships with torpedoes without ever being seen. Such attacks on merchant or passenger ships without giving the crews and passengers warning so they could escape in lifeboats was considered a violation of the laws of naval warfare, and became known as “unrestricted” submarine warfare. Germany engaged in such unrestricted warfare until  U-20  sunk the British passenger liner  Lusitania  off Ireland in May 1915. Over 1,200 lives were lost, including 128 Americans, and the US threatened to break diplomatic relations with Germany. The Imperial Navy subsequently instituted strict regulations for U-boat attacks, but those went by the boards in 1917 as the Germans tried to cut off supplies to Britain and starve the island nation into submission. It was a bad decision. The renewal of unrestricted submarine warfare and subsequent sinking of three American ships brought the US into the war, after which Germany’s fate was all but sealed.

WAR IN THE AIR

Airplanes had already seen limited military before World War I began. Italian aircraft were used for reconnaissance and small-scale bombing during the Italo-Turkish War of 1911. Aircraft during World War I continued to be used primarily for reconnaissance, including photo-reconnaissance missions. The first aircraft of the war weren’t even armed, since no serious effort had been made to create a fighting flying machine. Pilots began shooting at each other with pistols and rifles. Soon various schemes were attempted to attach machine guns to planes. The breakthrough came in 1915 when Holland’s Anthony Fokker developed a method to synchronize a machine gun’s fire with the rotation of the propeller on his  Eindecker  (single-wing) design for the German air force.

Early war planes were very light and used small engines with top speeds of less than 100 mph. On many designs the engine was in the rear and pushed the plane through the air. The demands of wartime, each side trying to outdo the other’s technological advances, created rapid improvements in aircraft design. Changes might occur within weeks; in the decades following the war, such changes would take years. By war’s end small, single-engine planes had been joined by multi-engine bombers such as the Giant, which Germany used to bomb British cities. Zeppelins were also used for reconnaissance and for bombing over land and sea. Tethered barrage balloons carried observers high above the front to watch enemy troop movements—and attracted the attention of the enemy’s airborne fighters.

While the war on the ground was a miserable existence in muddy, rat- and disease-infested trenches, and millions of lives might be spent to gain a few miles of territory, the war in the air captured the imagination of the world. Using this exciting new technology to maneuver through the skies and engage the enemy in one-on-one dogfights in which skillful pilots could rise to the status of ace gave the air war a sense of glamour that still hangs over the pilots of World War I.

AMERICA JOINS THE WAR

Most Americans saw little reason for the United States to involve itself in “the European War,” though some individuals—such as young pilots excited at the notion of flying in combat—enlisted through Canada or elsewhere. President Woodrow Wilson won reelection in 1916 on the slogan, “He kept us out of war.” That same year he tried to bring the combatant nations to the bargaining table to seek an end to the war that would be fair to all, but the attempt failed.

America was drawn into the conflict by the Zimmerman telegraph and unrestricted submarine warfare. On January 16, 1917, Foreign Secretary of the German Empire Arthur Zimmerman sent a coded message to the German ambassador in Mexico City, Heinrich von Eckart informing him Germany would return to unrestricted submarine warfare on February 1, a policy that might cause America to declare war. “We shall endeavor in spite of this to keep the United States of America neutral,” Zimmerman wrote, but if those efforts failed, Eckart was to convince Mexico to become Germany’s ally. As an inducement, Eckart was authorized to offer the return of the US states of Texas, New Mexico and Arizona to Mexico after America was defeated.

The code was broken, and the contents of the telegram published on March 1. Americans were outraged. Two weeks later German U-boats sank three American vessels. Wilson asked Congress on April 1 to authorize a declaration of war against Germany, which it did four days later. War was declared on the other Central Powers shortly thereafter.

When American troops and war materiel began arriving in Europe later in 1917, it unalterably shifted the balance of power in favor of the Allies. A final German offensive began on May 21, 1918, an attempt to win the war before the full weight of American strength could arrive. The Spring Offensive (also called the Ludendorff Offensive and the Kaiser’s Battle) sputtered out when German supply vehicles couldn’t keep up with the rapidly advancing soldiers across the broken, cratered battleground, and the Kaiser’s troops were left in poor defensive positions. An Allied operation that became known as the Hundred Days Offensive pushed the enemy back to the German border by September. Germany’s allies began their own peace negotiations.

The German navy mutinied. Ludendorff, architect of many German victories in the east, was dismissed. Riots broke out, often led by German Bolsheviks. Prince Max, Chancellor of Germany, authorized negotiations for peace terms and stipulated that both military and civilian representatives be involved. He then turned his title over to Friedrich Ebert, leader of the Socialist Democratic movement. Kaiser Wilhelm II abdicated on November 9. An agreement between the combatants called for all guns to fall silent on the 11th hour of the 11th day of the 11th month. Yet, even on the morning of November 11, before the designated time for the armistice to begin, some field officers ordered their men to make attacks, which accomplished little except more bloodshed.

THE ARMISTICE

A series of peace treaties were signed between the combatant nations, but the most significant was the Treaty of Versailles, signed on July 28, 1919, five years after Austria-Hungary had declared war on Serbia. Germany had hoped Woodrow Wilson would be a moderating factor that would allow for more generous peace terms, but the nations that had lost millions of young men to the weapons of the Central Powers were in no mood to be forgiving. As a result of the various treaties, the Ottoman Empire was dismantled. Austria-Hungary was broken into separate nations and forced to cede lands to successor states such as Czechoslovakia. Bulgaria was limited to a 20,000-man army, denied any aircraft or submarines and ordered to pay reparations over a 35-year period. Germany was restricted to a standing army of just 100,000 men, denied possession of certain weapons such as tanks, forced to pay reparations to its former enemies and give up all of its overseas colonies as well as some of its territories in Europe. In the coming years Germans would brood over the harsh terms and seek not only to overturn them but to inflict punishment on the nations that demanded them.

All combatant nations had concealed from their people the true extent of casualties during the war, but in Germany, where Hindenburg and Ludendorff were given control over virtually all aspects of civilian life as well as over the military, any negative reports about what was happening at the front were considered “defeatist” and were prohibited. Accordingly, much of the population believed it when they were told Germany was winning the war. The country’s sudden capitulation left them shocked and bewildered. Hindenburg claimed that the German soldier had been winning the war but was “stabbed in the back” by civilians who overthrew the monarchy. The popular old soldier was elected president of Germany, and his “stabbed in the back” myth was used to great effect by a rising political star, Adolf Hitler.

World War I

• More than 65 million men fought in the war.
• Dogs were used in the trenches to carry messages. A well-trained messenger dog was considered a very fast and reliable way to carry messages.
• It was the first major war where airplanes and tanks were used.
• Ninety percent of the 7.8 million soldiers from Austria-Hungary who fought in the war were either injured or killed.
• When the British first invented tanks they called them "landships."
• The terrorist group responsible for assassinating Archduke Ferdinand was called the Black Hand.
• Famed scientist Marie Curie helped to equip vans with x-ray machines that enabled French doctors to see bullets in wounded men. These vans were called "petites Curies", meaning "little Curies."
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US Entry Into World War I

By: History.com Editors

Updated: August 30, 2022 | Original: April 6, 2017

When World War I broke out across Europe in 1914, President Woodrow Wilson proclaimed the United States would remain neutral, and many Americans supported this policy of nonintervention. However, public opinion about neutrality started to change after the sinking of the British ocean liner Lusitania by a German U-boat in 1915; almost 2,000 people perished, including 128 Americans. Along with news of the Zimmermann telegram threatening an alliance between Germany and Mexico against America, Wilson asked Congress for a declaration of war against Germany. The United States officially entered the conflict on April 6, 1917.

World War I Begins

On June 28, 1914, Archduke Franz Ferdinand , heir to the throne of the Austro-Hungarian Empire, and his wife Sophie were assassinated by a Bosnian Serb nationalist in Sarajevo, the capital of the Austro-Hungarian province of Bosnia and Herzegovina.

One month later, on July 28, Austria-Hungary declared war on Serbia . Within a week, Russia, France, Belgium, Great Britain and Serbia had sided against Austria-Hungary and Germany, and the Great War, as it was originally called, was underway.

Central Powers

Germany and Austria-Hungary later teamed with the Ottoman Empire and Bulgaria and were referred to collectively as the Central Powers. Russia, France and Great Britain, the major Allied Powers, eventually were joined by Italy, Japan and Portugal, among other nations.

On August 4, as World War I erupted across Europe, President Woodrow Wilson proclaimed America’s neutrality, stating the nation “must be neutral in fact as well as in name during these days that are to try men’s souls.”

With no vital interests at stake, many Americans supported this position. Additionally, America was home to a number of immigrants from countries at war with each other and Wilson wanted to avoid this becoming a divisive issue.

American companies, however, continue to ship food, raw materials and munitions to both the Allies and Central Powers, although trade between the Central Powers and the United States was severely curtailed by Britain’s naval blockade of Germany. U.S. banks also provided the warring nations with loans, the bulk of which went to the Allies.

Lusitania Sinks

On May 7, 1915, a German submarine sank the British ocean liner Lusitania , resulting in the deaths of nearly 1,200 people, including 128 Americans. The incident strained diplomatic relations between Washington and Berlin and helped turn public opinion against Germany.

President Wilson demanded that the Germans stop unannounced submarine warfare; however, he didn’t believe the United States should take military action against Germany.

Some Americans disagreed with this nonintervention policy, including former president Theodore Roosevelt , who criticized Wilson and advocated going to war. Roosevelt promoted the Preparedness Movement, whose aim was to persuade the nation it must get ready for war.

'America First'

In 1916, as American troops were deployed to Mexico to hunt down Mexican rebel leader Pancho Villa following his raid on Columbus, New Mexico , concerns about the readiness of the U.S. military grew. In response, Wilson signed the National Defense Act in June of that year, expanding the Army and the National Guard, and in August, the president signed legislation designed to significantly strengthen the Navy.

After campaigning on the slogans “He Kept Us Out of War” and “America First,” Wilson was elected to a second term in the White House in November 1916.

Meanwhile, some Americans joined the fighting in Europe their own. Starting in the early months of the war, a group of U.S. citizens enlisted in the French Foreign Legion. (Among them was the poet Alan Seeger, whose poem “I Have a Rendezvous with Death” later was a favorite of President John F. Kennedy . Seeger was killed in the war in 1916.) Other Americans volunteered with the Lafayette Escadrille, a unit of the French Air Service, or drove ambulances for the American Field Service.

Submarine Warfare Resumes

In March 1916, a German U-boat torpedoed a French passenger ship, Sussex , killing dozens of people, including several Americans. Afterward, the United States threatened to cut diplomatic ties with Germany.

In response, the Germans issued the Sussex pledge, promising to stop attacking merchant and passenger ships without warning. However, on January 31, 1917, the Germans reversed course, announcing they would resume unrestricted submarine warfare, reasoning it would help them win the war before America, which was relatively unprepared for battle, could join the fighting on behalf of the Allies.

In response, America severed diplomatic ties with Germany on February 3. During February and March, German U-boats sank a series of U.S. merchant ships, resulting in multiple casualties.

Zimmermann Telegram

Meanwhile, in January 1917, the British intercepted and deciphered an encrypted message from German Foreign Minister Arthur Zimmermann to the German minister in Mexico, Heinrich von Eckhart.

The so-called Zimmermann telegram proposed an alliance between Germany and Mexico—America’s southern neighbor—if America joined the war on the side of the Allies.

As part of the arrangement, the Germans would support the Mexicans in regaining the territory they’d lost in the Mexican-American War— Texas , New Mexico and Arizona . Additionally, Germany wanted Mexico to help convince Japan to come over to its side in the conflict.

The British gave President Wilson the Zimmermann telegram on February 24, and on March 1 the American press reported on its existence. The American public was outraged by the news of the Zimmermann telegram and it, along with Germany’s resumption of submarine attacks, helped lead to the United States joining the war.

America Declares War on Germany

On April 2, 1917, Wilson went before a special joint session of Congress and asked for a declaration of war against Germany, stating: “The world must be made safe for democracy.”

On April 4, the Senate voted 82 to 6 to declare war. Two days later, on April 6, the House of Representatives voted 373 to 50 in favor of adopting a war resolution against Germany.

Among the dissenters was Rep. Jeannette Rankin of Montana , the first woman in Congress. It was only the fourth time Congress had declared war; the others were the War of 1812 , the Mexican-American War and the Spanish-American War of 1898.

In early 1917, the U.S. Army had just 133,000 members. That May, Congress passed the Selective Service Act , which reinstated the draft for the first time since the Civil War and led to some 2.8 million men being inducted into the U.S. military by the end of the Great War. Around 2 million more Americans voluntarily served in the armed forces during the conflict.

The first U.S. infantry troops arrived on the European continent in June 1917; in October, the first American soldiers entered combat in France. That December, America declared war against Austria-Hungary (America never was formally at war with the Ottoman Empire or Bulgaria).

When the war concluded in November 1918, with a victory for the Allies, more than 2 million U.S. troops had served at the Western Front in Europe, and more than 50,000 of them died.

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U.S. Entry into World War I, 1917. U.S. Department of State, Office of the Historian . Why did the US enter World War I? The University of Rochester Newscenter . U.S. Participation in the Great War (World War I). Library of Congress .

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