Causes of World War I
The immediate cause of the Great War, later to be
known as World War I, was the assassination of
Archduke Francis Ferdinand in Sarajevo, Bosnia, on
June 28, 1914. However, the main causes of the war
existed long before 1914.
At the time of his assassination, Francis Ferdinand, heir
to the throne of the Austro-Hungarian Empire, had
been visiting Bosnia, a new Austro-Hungarian province.
He was shot by Gavrilo Princip, a 19-year-old Bosnian
nationalist who believed that Austria-Hungary had no
right to rule Bosnia.
Main Causes of World War I
Imperialism: Competition for colonial lands in Africa and
elsewhere led to conflict among the major European powers.
Militarism: By the early 1900s, powerful nations in Europe had
adopted policies of militarism, or aggressively building up armed
forces and giving the military more authority over government and
Nationalism: One type of nationalism inspired the great powers of
Europe to act in their own interests. Another emerged as ethnic
minorities within larger nations sought self-government.
Alliances: In a complicated system of alliances, different groups of
European nations had pledged to come to one another’s aid in the
event of attack.
The Conflict Expands
Convinced that Serbia was behind the Archduke’s assassination, AustriaHungary declared war on Serbia on July 28, 1914.
Russia, as Serbia’s protector, began mobilization, or the readying of troops
France, Russia’s ally, and Germany, Austria-Hungary’s ally, also began
Germany, located between France and Russia, wanted to conquer France
quickly to avoid the need to fight on two fronts. To get to France, German
forces had to pass through neutral Belgium; the invasion of Belgium
brought Britain into the conflict as well.
One week after the war started, all the great powers of Europe had been
drawn into it. Germany and Austria-Hungary formed the Central Powers,
while Russia, France, Serbia, and Great Britain were called the Allies.
Stalemate and Modern Warfare
By September 1914, the war had reached a stalemate, a
situation in which neither side is able to gain an
When a French and British force stopped a German
advance near Paris, both sides holed up in trenches
separated by an empty “no man’s land.” Small gains in
land resulted in huge numbers of human casualties.
Both sides continued to add new allies, hoping to gain
Stalemate and Modern Warfare
Neither soldiers nor officers were prepared for the new,
highly efficient killing machines used in World War I.
Machine guns, hand grenades, artillery shells, and
poison gas killed thousands of soldiers who left their
trenches to attack the enemy.
As morale fell, the lines between soldiers and civilians
began to blur. The armies began to burn fields, kill
livestock, and poison wells.
The American Response
Because many Americans were European immigrants or the
children of European immigrants, many felt personally
involved in the escalating war. Although some had
sympathies for the Central Powers, most Americans
supported the Allies.
Support for the Allies was partially caused by Germany’s rule
by an autocrat, a ruler with unlimited power. In addition,
anti-German propaganda, or information intended to sway
public opinion, turned many Americans against the Central
To protect American investments overseas , President
Wilson officially proclaimed the United States a neutral
country on August 4, 1914.
The Committee on Public
Information: Propaganda Agency
German Submarine Warfare
To break a stalemate at sea, Germany began to employ
U-boats, short for Unterseeboot, the German word for
submarine. U-boats, traveling under water, could sink
British supply ships with no warning.
When the British cut the transatlantic cable, which
connected Germany and the United States, only news
with a pro-Allied bias was able to reach America.
American public opinion was therefore swayed against
Germany’s U-boat tactics.
Sinking of the Lusitania and the Sussex
The Sinking of the Lusitania
On May 7,1915, a German U-boat sank the British passenger liner
Lusitania, which had been carrying both passengers and weapons for
Since 128 American passengers had been on board, the sinking of
the Lusitania brought the United States closer to involvement in the
The Sussex Pledge
More Americans were killed when Germany sank the Sussex, a
French passenger steamship, on March 24,1916.
In what came to be known as the Sussex pledge, the German
government promised that U-boats would warn ships before
attacking, a promise it had made and broken before.
Moving Toward War
Unrestricted Submarine Warfare
On January 31, 1917, Germany announced its intent to end the Sussex pledge
and return to unrestricted submarine warfare.
This action caused the United States to break off diplomatic relations with
Despite this announcement, the German navy did not attack any American
ships in February, causing the United States to continue to hope for peace.
The Zimmermann Note
During this time, Britain revealed an intercepted telegram to the government of
Mexico from Germany’s foreign minister, Arthur Zimmermann.
In this telegram, known as the Zimmermann note, Germany offered to return
American lands to Mexico if Mexico declared war on the United States.
Neither Mexico nor President Wilson took the Zimmermann note seriously, but
it brought America closer to entering the war.
The War Resolution
When the Russian Revolution replaced Russia’s
autocratic czar with a republican government in March
1917, the United States no longer needed to be
concerned about allying itself with an autocratic nation.
This removed one more stumbling block to an
American declaration of war.
As Germany continued to sink American ships in
March, President Wilson’s patience for neutrality wore
out. On April 6, 1917, the President signed Congress’s
war resolution, officially bringing the United States into
Moving Toward War
Building an Army
Despite the preparedness movement, the United States lacked a large
and available military force. Congress therefore passed a Selective
Service Act in May 1917, drafting many young men into the military.
Draftees, volunteers, and National Guardsmen made up what was
called the American Expeditionary Force (AEF), led by General John
Training for War
New recruits were trained in the weapons and tactics of the war by
American and British lecturers at new and expanded training camps
around the country.
Ideally, the military planned to give new soldiers several months of
training. However, the need to send forces to Europe quickly
sometimes cut training time short.
Turning the Tide of War
New methods of military transportation, including tanks, airplanes, and
German zeppelins, or floating airships, influenced the manner in which the
war was fought.
In the spring of 1918, Germany provided safe passage for Vladimir Lenin,
leader of the Russian Bolsheviks, from Switzerland to Russia. The
Bolsheviks successfully overthrew the Russian republican government and
made peace with Germany.
The resulting truce ceded valuable Russian land to Germany and also
meant that the German military could concentrate exclusively on the
Western front. Before the arrival of American troops, Germany was able to
gain ground in France, coming within 50 miles of Paris.
General Pershing’s troops, however, pushed back the Germans in a series of
attacks. Finally, the German army was driven to full retreat in the MeuseArgonne Offensive begun on September 26, 1918.
Ending the War
In the face of Allied attacks and domestic revolutions, the
Central Powers collapsed one by one. Austria-Hungary
splintered into smaller nations of ethnic groups, and German
soldiers mutinied, feeling that defeat was inevitable.
When the Kaiser of Germany fled to Holland, a civilian
representative of the new German republic signed an armistice,
or cease-fire, in a French railroad car at 5am on November 11,
Although guns fell silent six hours later, many more deaths
were to follow. The influenza epidemic of 1918 killed more
people, both in the United States and Europe, than all of the
Results of the War
Dead and Wounded: The estimated death toll of World War I
was 8 million soldiers and civilians, including tens of thousands
of Americans. Many more had lost limbs or been blinded by
poison gas. However, the efforts of the Red Cross and other
agencies had helped save many lives.
Loss of Young Men: Many sensed that the war had destroyed an
entire generation of young men and grieved for the loss of their
talents and abilities.
Genocide: In an act of genocide, or organized killing of an
entire people, the Ottoman Empire had murdered hundreds of
thousands of Armenians suspected of disloyalty to the
Enforcing American Loyalty
Fear of Foreigners: Fear of espionage, or spying, was
widespread; restrictions on immigration were called for and
“Hate the Hun”: The war spurred a general hostility toward
Germans, often referred to as Huns in reference to European
invaders of the fourth and fifth centuries. German music,
literature, language, and cuisine became banned or
Repression of Civil Liberties: Despite Wilson’s claim that the
United States fought for liberty and democracy, freedom of
speech was reduced during the war. Sedition, or any speech
or action that encourages rebellion, became a crime.
President Wilson’s Proposals
As the war neared an end, President Wilson developed a program for
peace around the world known as the Fourteen Points, named for
the number of provisions it contained.
One of Wilson’s Fourteen Points called for an end to entangling
alliances; another involved a reduction of military forces. Another
dealt with the right of Austria-Hungary’s ethnic groups to selfdetermination, or the power to make decisions about their own
Although both Wilson and the German government assumed that
the Fourteen Points would form the basis of peace negotiations, the
Allies disagreed. During peace negotiations, Wilson’s Fourteen
Points were discarded one by one.
The Paris Peace Conference
Wilson Forced to Compromise
Although Wilson claimed that he was not interested in the spoils, or
rewards, of war, his Allied colleagues were interested in making the Central
Powers pay for war damages.
Wilson was forced to compromise on his views, especially concerning selfdetermination for former German colonies.
The League of Nations
One of Wilson’s ideas, the formation of a League of Nations, was agreed
upon at the Paris Peace Conference. The League of Nations was designed to
bring the nations of the world together to ensure peace and security.
Republicans in Congress, however, were concerned about Article 10 of the
League’s charter, which contained a provision that they claimed might draw
the United States into unpopular foreign wars.
The Peace Treaty
The treaty which was negotiated at the Paris Peace Conference
redrew the map of Europe to the Allies’ advantage.
Nine new nations were created from territory taken from AustriaHungary, Russia, and Germany. Although most borders were drawn
with the division of ethnic minorities in mind, the redivisions
created new ethnic minorities in several countries.
France insisted that Germany be humiliated and financially crippled.
The peace treaty required Germany to pay billions of dollars in
reparations, or payment for economic injury suffered during the war.
Wilson, however, opposed this plan, claiming that these demands
would lead to future wars.
On June 28, 1919, the peace treaty, which came to be known as the
Versailles Treaty, was signed at Versailles, outside of Paris.
Reactions at Home
Congress and the Treaty of Versailles
Despite Wilson’s intensive campaign in favor of the
Versailles Treaty, Congress voted against ratifying it in
The United States declared the war officially over on
May 20, 1920. It ratified separate peace treaties with
Germany, Austria, and Hungary. However, the United
States did not join the newly formed League of
Reactions at Home
Difficult Postwar Adjustments
The war had given a large boost to the American
economy, making the United States the world’s largest
Soldiers returned home to a hero’s welcome but found
that jobs were scarce.
African American soldiers, despite their service to their
country, returned to find continued discrimination.
Many American artists entered the postwar years with a
sense of gloom and disillusionment.