Introduction to World War I
World War I, primarily centered in Europe but spreading globally, lasted from July 28, 1914, to November 11, 1918. Spanning approximately four years, three months, and fourteen days, this massive conflict involved around 70 million soldiers. It was known as “the war to end all wars” or “the Great War” because contemporary people believed this war would end all human conflicts and prevent future devastation.
Previous wars, such as the Napoleonic Wars (1803-1815) or the Crimean War (1853-1856), were mainly fought on a regional level or limited to two or three countries, like the Franco-Prussian War (1870-71). World War I was the first war in which almost all major countries of the world were embroiled. Various nations supported one side or another, making it a global conflict.
The Opposing Powers
The Allied Powers included Britain, France, Russia, Italy (from 1915), the United States (from 1917), Japan, Canada, Australia, New Zealand, India (as a British colony), and other nations. The Central Powers consisted of Germany, Austria-Hungary, the Ottoman Empire (Turkey), Bulgaria, and some smaller allies.
For the first time in history, people of different races—white (European), yellow (Asian, including Japanese, Chinese, and Indian soldiers), black (African colonial soldiers, such as Senegalese and South Africans), and brown (Middle Eastern, including Arabs and Turks)—were forced to take up arms against each other due to the widespread use of colonial armies.
Most significantly, the flames of war spread from east to west, north to south, and from land to water and sky. This war saw the invention and use of new warfare methods that caused mass destruction and terror, including chemical weapons, tanks, aircraft, submarines, and machine guns.
Revolutionary Warfare Technology
Traditional direct attack-counterattack warfare systems were replaced by new military technology and trench warfare, where millions of soldiers remained trapped in trenches filled with mud, rats, diseases, and constant shelling for years. Sometimes soldiers had to stay in the same position for months.
The Human and Economic Toll
Approximately 16 million soldiers and civilians died in this war, including 9 to 11 million soldiers and 6 to 13 million civilians. Additionally, about 21 million people were wounded, and 7 million became permanently disabled.
The economic damage was also immense. Both sides spent approximately $1.86 trillion, and property destruction exceeded one trillion dollars. France lost 25 percent of its land, and Belgium’s economy was 50 percent destroyed. This war was not only a symbol of human loss but also an example of the cruelty and technology of modern warfare.
Major Causes of World War I
The fear of world war had been looming since the end of the 19th century. German Chancellor Otto von Bismarck predicted in 1898 in Berlin: “I will not see the world war, but you will, and it will begin in Western Asia.”
Although Bismarck betrayed Russia by taking Austria’s side at the 1878 Berlin Congress, as long as he remained in power, he did not allow friendship between France and Russia. After Bismarck, Germany had no such far-sighted politician who could improve the deteriorating situation.
The world war could actually have started in 1909 if Russia had decided to confront Austria over the Bosnia and Herzegovina question. However, Russia’s position was not strong at that time after its defeat in the 1904-05 Russo-Japanese War, so the war was postponed.
1. Imperialist Ambitions
The causes of World War I were very clear—first trade and later the Industrial Revolution caused European countries’ imperialist ambitions to grow day by day. As long as Bismarck was in power in Germany, he made no attempt to compete with England in this regard. However, after Bismarck, Germany also attempted to establish its own colonies.
By the end of the 19th century, the possibility of new colonies had ended, causing imperialist countries to begin grabbing colonies from each other, and war became inevitable.
Additionally, there were some traditional imperialist desires:
- France wanted control of Morocco
- Russia wanted Iran, Constantinople, and other territories of the Ottoman Empire
- This brought Russia into conflict with Germany
- Britain also felt threatened for its Asian colonies
- Austria was also taking interest in these matters
The combined effect was that tremendous competition began in international trade, which worried Britain the most. When Germany wanted to control the Ottoman Empire’s economy and planned to lay a railway line from Berlin to Baghdad, Britain, France, and Russia were alarmed by this German plan.
2. Political Treaties and Alliance System
A major cause of World War I was political treaties and alliance formation. From the end of the 19th century, Europe began dividing into two military camps.
The Triple Alliance (1882):
- Germany and Austria-Hungary formed a dual alliance in 1879
- Italy joined in 1882, creating the Triple Alliance
- Bismarck’s main foreign policy objective was to keep France isolated
The Triple Entente (1907):
- After Bismarck’s fall in 1890, France and Russia formed an alliance in 1894
- Britain abandoned its “splendid isolation” policy
- Britain formed an alliance with Japan in 1902
- Britain and France formed an entente in 1904
- France, Russia, and Britain created the “Cordial Triple Entente” in 1907
Thus, all of Europe was divided into two military blocs. When World War I began, Italy switched sides after seeing the Allies’ assured victory and joined the war against the Triple Alliance in 1915 due to Allied inducements. This kind of alliance formation made it clear that even a small dispute could take the form of a world war.
3. The Spread of Militarism
From the beginning of the 20th century, an arms race had started among European countries. To maintain colonial and commercial dominance outside Europe and due to ethnic polarization and traditional enmity within Europe, an arms race began, and military activities intensified.
Large-scale recruitment of soldiers, massive production of deadly weapons, and intellectual efforts glorifying wars created a war mentality throughout Europe. Trotsky praised the principle of “might is right” in his work “Politics.” French philosophers also encouraged similar militarist sentiments. Thus, the aggressive spirit of militarism was constantly pushing European nations toward war.
Additionally, newspapers published in various countries played an important role in starting the war, inflaming public emotions and making it impossible to control the situation. Thus, one cause of war was the poisoning of public ideology through newspapers in all major countries.
4. The Spirit of Nationalism
Along with nationalism, clashes among European countries over colonies and trade were inevitable, but some internal factors also proved very important. The spread of aggressive nationalist sentiments in various European countries played an important role not only in starting the world war but also in expanding it.
Pan-Slavism:
- Russia launched a polarization movement based on the Slavic race
- The plan included merging many Balkan countries of the Ottoman Empire with Russia
- Leadership was given to Serbia
- Slavic people also lived in Austria-Hungary, which felt threatened
Pan-Germanism:
- Like Russia’s Pan-Slav movement, Germany had a “Pan-German” movement
- The objective was to unite Germans living in various European states under one great Germany
- This aggressive spirit of nationality created political chaos throughout Europe
5. Territorial Problems
Alsace and Lorraine:
- Long-standing enmity between France and Germany
- France wanted revenge for its 1870-71 defeat
- France wanted to recover its lost provinces—Alsace and Lorraine
- These were considered symbols of Louis XIV’s conquest
- Lorraine had iron mines, giving it economic and industrial importance
Bosnia and Herzegovina:
- By the 1878 Berlin Treaty, these provinces were given to Austria for administration
- Austria couldn’t incorporate them into its state initially
- In 1908, Austria annexed both provinces, violating the Berlin Treaty
- Since Bosnia and Herzegovina were mainly inhabited by Slavic people, Serbia opposed this
- Russia wasn’t ready for war at that time, or the world war would have started then
6. Kaiser Wilhelm II’s Ambitions
Germany’s ruler Kaiser Wilhelm II is considered the originator of World War I. As long as Bismarck was in power in Germany, he always followed the policy of keeping France isolated and not competing with England.
Kaiser Wilhelm was extremely ambitious and wanted to become a world conqueror through military strength. His land army was very powerful, but he wasn’t satisfied. He wanted to make his navy as powerful as his army. Wilhelm’s policy naturally worried England.
Wilhelm declared: “Our future depends on the sea… I will not rest until my navy becomes as powerful as my army.” At another place, he said: “We need more navy, army, and gunpowder.” Not only this, he threatened the Allied nations: “If they want war, they can start war; we are not afraid of war.”
Wilhelm’s speeches made Europe’s atmosphere tense. England initially wanted to befriend Germany, but Kaiser Wilhelm II rejected this proposal, saying that Berlin’s path goes through Austria. Wilhelm also began expanding eastward, and when he proposed building the Berlin-Baghdad railway line, England opposed Germany. Thus, World War I began due to Kaiser Wilhelm’s policies.
Pre-War Crises
Outside and inside Europe, there were several occasions when the possibility of world war appeared before 1914:
Morocco Crisis:
- France and England clashed over Morocco
- 1904 treaty: Britain recognized French authority in Morocco
- In exchange, France gave Britain concessions
- When Germany intervened in Morocco in opposition, France satisfied it in 1911
Bosnia-Herzegovina Crisis (1908):
- Austria annexed Bosnia and Herzegovina, which Serbia coveted
- Russia declared war in support of Serbia
- Germany’s support for Austria prevented Russia from advancing
- This made the situation in Europe tense
Control attempts over newly liberated countries of the Ottoman Empire in the Balkan Peninsula further increased tension among European countries.
The Immediate Cause: Sarajevo Assassination
The immediate cause of World War I was the Sarajevo assassination. On June 28, 1914, Archduke Franz Ferdinand, heir to Austria-Hungary, and his wife Sophie were assassinated in Sarajevo, the capital of Bosnia, by Serbian nationalist Gavrilo Princip.
Gavrilo Princip was a member of “United States of Slavs,” affiliated with the “Black Hand” organization. This organization was part of the Pan-Slav movement, which opposed Austria’s control over Bosnia-Herzegovina. Austria had seized these territories in 1908, while Serbia considered them its part. Austria called this assassination a Serbian conspiracy and held the Serbian government responsible.
The July Crisis
On July 23, 1914, Austria sent Serbia a letter with harsh conditions, demanding action against terrorists and permission for Austrian officials to investigate. Serbia was given a 48-hour ultimatum to accept. This was humiliating for Serbia, yet it accepted some conditions of the letter. However, Austria was not satisfied with Serbia’s response.
On July 5, 1914, Germany gave Austria its support, and subsequently, Austria declared war on Serbia on July 28, 1914. British Foreign Minister Sir Edward Grey attempted to avert war but failed.
War Expansion and Commencement
Due to its alliance with Serbia, Russia declared war against Austria because Russia was Serbia’s allied partner. In response, Germany declared war on Russia on August 1, 1914, and on France on August 3, 1914.
England was still hesitant to participate in the war and was trying to avert it. British Foreign Minister Grey clearly told the French ambassador that England would not participate in this war. Grey also demanded assurance from France and Germany to accept Belgium’s neutrality. France agreed, but Germany gave no response.
When German armies entered Belgium, violating the 1839 London Treaty to pressure France, Britain declared war on Germany on August 4, 1914. Thus, due to alliances, this dispute transformed into a global war, and World War I began.
War Responsibility
Both sides held each other responsible for starting World War I. German Chancellor Bethmann blamed England’s foreign policy for causing the war. Conversely, British Foreign Minister Grey held Germany responsible.
According to Grey, after Bismarck’s death, the Cordial Entente was established against the Triple Alliance, and rivalry between both blocs became one of many causes of the 1914 world war. This war shattered the German Empire. Whatever the case, no single country or alliance can be held entirely responsible for the Great War, and both blocs should share responsibility for starting the world war.
Major Events of World War I
World War I was fought on several fronts from 1914 to 1918, including the Western Front, Eastern Front, Balkan Front, Middle Eastern Front, and naval and aerial warfare. This war is known for its complexity, global expansion, and unprecedented destruction.
1914: War’s Beginning and Initial Offensives
World War I began on July 28, 1914, with Austria-Hungary’s declaration of war against Serbia. Subsequently, due to alliances, the war rapidly spread throughout Europe and the world.
Germany’s Belgian Invasion (Schlieffen Plan)
Germany implemented its Schlieffen Plan at the war’s beginning, aiming to quickly defeat France on the Western Front and then face Russia on the Eastern Front. Under this plan, Germany invaded neutral Belgium on August 4, 1914, to bypass France’s strong border defense (Maginot Line).
Belgium’s neutrality was guaranteed by the 1839 London Treaty, and Germany’s step forced Britain to join the war. Germany easily conquered Belgian fortresses like Liège, but Belgian and British Expeditionary Force resistance slowed Germany’s pace. This invasion laid the foundation for trench warfare on the Western Front.
First Battle of the Marne (September 1914)
German armies had reached near Paris, but in September 1914, French and British combined forces stopped the German army at the First Battle of the Marne. In this battle, French General Joseph Joffre used Paris taxis to send soldiers to the front—a famous incident in war history.
This battle shattered Germany’s hope of quick victory and created a stalemate on the Western Front. After this, both sides started trench warfare, with soldiers settling into trenches hundreds of kilometers long.
Battle of Tannenberg (August 1914)
On the Eastern Front, Germany achieved a major victory against Russia. In the August 1914 Battle of Tannenberg, German Generals Paul von Hindenburg and Erich Ludendorff almost destroyed the Russian Second Army.
In this battle, 78,000 Russian soldiers were killed or wounded, and 92,000 were taken prisoner. This was Germany’s biggest early victory, exposing Russia’s military weakness. However, Russia continued the war on the Eastern Front, forcing Germany to fight on two fronts.
Japan’s War Entry and Capture of German Colonies
On August 23, 1914, Japan declared war on Germany under alliance with the Allied nations. Japan captured German colonies, such as Qingdao in China and Pacific islands. This was the war’s first global expansion, as it spread beyond Europe to Asia.
British colonies like India, Australia, and New Zealand also sent soldiers, making the war’s nature even more global.
Beginning of Trench Warfare
By the end of 1914, both sides on the Western Front had built a series of trenches from Switzerland to the North Sea. In this trench warfare, soldiers struggled to survive amid mud, disease, and constant shelling.
In 1914, the “Christmas Truce” was a notable incident where German and British soldiers observed a ceasefire at some locations on the Western Front, celebrated Christmas, and met each other. This was a rare moment of humanity in war.
1915: War Expansion and New Strategies
In 1915, new countries joined the world war, and the war’s cruelty increased. Both sides employed new strategies and weapons.
Italy’s Entry on Allied Side
In May 1915, Italy left the Triple Alliance and joined the war on the Allied side according to the London Treaty. Italy was promised South Tyrol, Istria, and Dalmatia from Austria-Hungary.
Italy started war against Austria in the Alps, but trench warfare and cold in mountainous regions caused heavy losses to both sides. Italy’s entry was a strategic advantage for the Allies, as it forced Austria to fight on another front.
Gallipoli Campaign (February 1915-January 1916)
The Allied nations, especially Britain and France, launched the Gallipoli Campaign to weaken the Ottoman Empire. The objective was to control the Dardanelles Strait to send supplies to Russia via the Black Sea route. Australian and New Zealand soldiers participated in this campaign.
Under Mustafa Kemal’s (later Atatürk) leadership, the Turkish army offered strong resistance, causing heavy losses to the Allied nations, who had to withdraw in January 1916. This was the Allies’ biggest strategic defeat, which strengthened Turkey.
Battle of Ypres and Chemical Weapons (April-May 1915)
In the Second Battle of Ypres in April 1915, Germany used chemical weapons (chlorine gas) on a large scale for the first time. This gas destroyed soldiers’ lungs and was very horrific.
Canadian soldiers participated on a large scale for the first time in this battle, and their resistance saved the Allied nations from defeat. The use of chemical weapons became a symbol of war’s cruelty, and later both sides began using more deadly gases like mustard gas.
Beginning of Submarine Warfare
Germany started submarine warfare in 1915, aiming to destroy Britain’s maritime supplies. On May 7, 1915, German submarine U-20 sank the British passenger ship Lusitania, killing 1,198 people, including 128 American citizens.
This incident inflamed American public opinion against Germany and later became one reason for America’s entry into the war.
War in the Middle East
Against the Ottoman Empire, the Allies launched campaigns in the Middle East. In Mesopotamia (modern Iraq), British forces advanced toward Baghdad, but Turkey besieged the British army at Kut-al-Amara, forcing surrender in 1916. This was another Allied defeat.
1916: War’s Peak Cruelty
1916 was World War I’s bloodiest year, with massive battles and heavy losses to both sides. This year is also known for trench warfare and use of new technologies. Major military events this year included the Battle of Verdun, Battle of Jutland, Battle of the Somme, and Brusilov Offensive—indicators of war’s destructive nature.
Battle of Verdun (February-December 1916)
The Battle of Verdun was part of Germany’s strategy, aiming to weaken France’s army by “bleeding it white.” German General Erich von Falkenhayn attacked Verdun’s fortresses, which were France’s symbolic and strategic center.
French General Philippe Pétain raised his army’s morale with the slogan “They shall not pass.” This battle continued for 10 months, with over 700,000 soldiers from both sides killed or wounded. This battle was costly for Germany too, with no clear victor emerging.
Battle of Jutland (May-June 1916)
The Battle of Jutland in the North Sea was World War I’s largest naval battle, fought between the British Royal Navy and German High Seas Fleet. Britain lost 14 ships and approximately 6,000 soldiers, while Germany lost 11 ships and about 2,500 soldiers.
Strategically, Britain’s control over the sea remained, and it made Germany’s blockade even stricter. This battle proved important in limiting Germany’s maritime ambitions.
Battle of the Somme (July-November 1916)
The Allied nations started the Battle of the Somme to pressure Germany, which proved most destructive for the British army. On the first day, July 1, 1916, 57,470 British soldiers became casualties.
Britain used tanks for the first time on September 15, 1916, in this battle—a symbol of technological innovation in warfare. However, tanks were initially unreliable and couldn’t provide significant advantage in battle. Overall, over 1 million soldiers became casualties in the Battle of the Somme.
Brusilov Offensive (June-September 1916)
On the Eastern Front, Russia launched the Brusilov Offensive, which was the war’s most successful Russian campaign. General Alexei Brusilov inflicted heavy damage on the Austria-Hungary army, with 1.5 million Austrian soldiers becoming casualties or prisoners.
However, Russia also lost 500,000 soldiers, and this campaign weakened Russia’s economy and army, which later became one cause of the Russian Revolution.
1917: War Transformation and Global Participation
Major changes came to the war in 1917, including America’s entry and Russia’s exit. This year was important in determining the war’s outcome.
America’s Entry into War
On May 7, 1915, German submarine U-20 sank the British passenger ship RMS Lusitania, killing 1,198 people. Among these dead were 128 American citizens. After this, Germany started unlimited submarine warfare in 1917, targeting all ships.
In January 1917, German Foreign Minister Arthur Zimmermann sent a telegram to Mexico, proposing Mexico join war against America. Britain intercepted this telegram and handed it to America. These events turned American public opinion against Germany, and on April 6, 1917, America declared war on Germany.
America provided 2 million soldiers and economic resources, which ensured the Allied nations’ victory.
Russian Revolution and War Withdrawal
The war caused severe economic and social crisis in Russia. In March 1917, the February Revolution removed Tsar Nicholas II from power, and the provisional government continued the war.
In October 1917, under Lenin’s leadership in the Bolshevik Revolution, communists seized power, and the Bolshevik government signed the Treaty of Brest-Litovsk on March 3, 1918. Under this, Russia withdrew from the war and handed over territories like Poland, Ukraine, the Baltics, and Finland to Germany.
This was a big victory for Germany, as now it could focus on the Western Front.
Battle of Passchendaele (July-November 1917)
The Third Battle of Ypres, also called the Battle of Passchendaele, was the British army’s attempt to capture German submarine bases. Heavy rain and mud made the battle even more horrific. Both sides suffered over 500,000 casualties, but the Allied nations couldn’t gain strategic advantage. This battle is a symbol of trench warfare’s cruelty.
Battle of Caporetto (October-December 1917)
In the Battle of Caporetto between Italy and Austria, German and Austrian armies defeated Italy. 300,000 Italian soldiers became casualties or were taken prisoner, and Austria captured a large part of Italy. However, the Allied nations saved Italy by sending support.
1918: War’s End and Allied Victory
In 1918, the war reached its final phase. The Allied nations united to defeat Germany, and for several other reasons, the war ended.
Spanish Flu Pandemic
The Spanish Flu pandemic spread in 1918, killing 50 million people worldwide, including soldiers and civilians. This pandemic weakened both sides’ armies in the war’s final phase. It spread rapidly in soldiers’ crowded trenches, affecting military campaigns.
Allies’ Final Campaign (August-November 1918)
In July 1918, the Allied nations started the Hundred Days Offensive, with British, French, American, and Canadian armies launching a joint attack. In the Second Battle of the Marne and Battle of Amiens, the Allied nations pushed Germany back.
Tanks, aircraft, and coordinated strategy gave the Allies an edge. Subsequently, Bulgaria surrendered on September 30, the Ottoman Empire on October 30, and Austria-Hungary on November 3.
German Revolution
Due to war defeat and economic crisis in Germany, revolution started in Berlin on November 8, 1918. Kaiser Wilhelm II had to abandon power and flee to the Netherlands. The Weimar Republic was established in Germany.
Armistice (November 11, 1918)
On November 11, 1918, at 11 AM, Germany signed the armistice treaty in a railway carriage in Compiègne Forest, France. Under this, Germany withdrew its armies, demilitarized the Rhineland, and handed over war materials. This was the war’s formal end.
Paris Peace Conference
After World War I’s end, the Paris Peace Conference was organized on January 18, 1919, in France’s capital Paris, with the objective of establishing peace and laying the foundation for a new world order for the future.
Representatives from 32 countries participated in this conference, including Allied nations’ prominent leaders like American President Woodrow Wilson, British Prime Minister David Lloyd George, French Prime Minister Georges Clemenceau, and Italian Prime Minister Vittorio Orlando.
This conference started at the Palace of Versailles, and its main objective was to address war consequences, impose conditions on defeated Central Powers, and prepare a framework for global peace.
The Major Treaties
The conference resulted in five major treaties, the most important being the Treaty of Versailles, signed on June 28, 1919. This treaty held Germany primarily responsible for the war and imposed harsh punishments. Other treaties included:
- Treaty of Saint-Germain (Austria, September 10, 1919)
- Treaty of Neuilly (Bulgaria, November 27, 1919)
- Treaty of Trianon (Hungary, June 4, 1920)
- Treaty of Sèvres (Ottoman Empire, August 10, 1920)
The Treaty of Versailles was considered a “Diktat” (imposed treaty) in Germany, because Germany wasn’t given any participation, causing humiliation and economic crisis that gave birth to discontent in Germany.
Wilson’s Fourteen Points
Woodrow Wilson’s 14 Points, especially national self-determination and establishment of the League of Nations, shaped the conference. However, Clemenceau’s retaliatory policy and Lloyd George’s balanced perspective created conflict, making the treaty controversial.
The establishment of the League of Nations on January 10, 1920, was a positive result of the conference, but Germany and Russia’s exclusion weakened its effectiveness. Thus, the Paris Peace Conference ended the war, but its harsh conditions laid the foundation for World War II.
Consequences of World War I
World War I’s consequences were deep and long-lasting on human, political, economic, social, and ideological levels, changing the direction of the 20th century.
Human Toll
- Approximately 16 million people died, including 9-11 million soldiers and 6-13 million civilians
- 21 million wounded and 7 million permanently disabled
- The 1918-20 Spanish Flu pandemic killed 50 million more people
Political Changes
The war ended four major empires—German, Austria-Hungary, Ottoman, and Russian—giving birth to new independent nations:
- Poland
- Czechoslovakia
- Yugoslavia
- Latvia, Lithuania, and Estonia
The League of Nations (1920) was established for global peace.
Economic Impact
The war devastated Europe’s economy:
- Both sides spent $1.3 trillion
- Over $1 trillion in property destruction
- France and Belgium lost 25-50% of their economies
- Heavy reparations, inflation, and unemployment created economic instability in Germany
- America became the center of world political-economic influence
Social Transformation
The war changed social structures significantly:
Women’s Rights:
- Women worked in factories, hospitals, and the military during the war
- This gave momentum to suffrage movements
- Britain (1918), Germany (1919), and America (1920) granted women voting rights
Anti-War Sentiment:
- War’s cruelty gave birth to anti-war feelings
Rise of Ideologies:
- The 1917 Bolshevik Revolution gave birth to communism
- Communist government was established in Russia
- Treaty of Versailles’ humiliation inspired fascism in Italy and Nazism in Germany
- Inspired independence movements in colonial countries
Long-Term Impact
World War I fundamentally transformed the global landscape, setting the stage for major 20th-century developments. The harsh terms of the peace treaties, particularly the Treaty of Versailles, created resentment that would eventually contribute to World War II. The war also accelerated technological advancement, changed social norms, and reshaped international relations for generations to come.
The Great War remains a pivotal moment in human history—a conflict that demonstrated both the destructive potential of modern warfare and humanity’s capacity for resilience and reconstruction in the face of unprecedented tragedy.
