World War I 1914–1918
World War I, also called First World War or Great War, an international conflict that in 1914–18 embroiled most of the nations of Europe along with Russia, the United States, the Middle East, and other regions. The war pitted the Central Powers—mainly Germany, Austria-Hungary, and Turkey—against the Allies—mainly France, Great Britain, Russia, Italy, Japan,
and, from 1917, the United States. It ended with the defeat of the
Central Powers. The war was virtually unprecedented in the slaughter,
carnage, and destruction it caused.
A British soldier inside a trench on the Western Front during World War I, 1914–18.Hulton Archive/Getty Images
World War I was one of the great watersheds of 20th-century geopolitical history. It led to the fall of four great imperial dynasties (in Germany, Russia, Austria-Hungary, and Turkey), resulted in the Bolshevik Revolution in Russia, and, in its destabilization of European society, laid the groundwork for World War II.
A collection of significant facts about World War I.Encyclopædia Britannica, Inc.
The outbreak of war
With Serbia already much aggrandized by the two Balkan Wars (1912–13, 1913), Serbian nationalists turned their attention back to the idea of “liberating” the South Slavs of Austria-Hungary. Colonel Dragutin Dimitrijević, head of Serbia’s military intelligence, was also, under the alias “Apis,” head of the secret society Union or Death, pledged to the pursuit of this pan-Serbian ambition. Believing that the Serbs’ cause would be served by the death of the Austrian archduke Franz Ferdinand, heir presumptive to the Austrian emperor Franz Joseph, and learning that the Archduke was about to visit Bosnia on a tour of military inspection, Apis plotted his assassination. Nikola Pašić,
the Serbian prime minister and an enemy of Apis, heard of the plot and
warned the Austrian government of it, but his message was too cautiously
worded to be understood.
At 11:15 am on June 28, 1914, in the Bosnian capital, Sarajevo, Franz Ferdinand and his morganatic wife, Sophie, duchess of Hohenberg, were shot dead by a Bosnian Serb, Gavrilo Princip. The chief of the Austro-Hungarian general staff, Franz, Graf (count) Conrad von Hötzendorf, and the foreign minister, Leopold, Graf von Berchtold, saw the crime as the occasion for measures to humiliate Serbia and so to enhance Austria-Hungary’s prestige in the Balkans. Conrad had already (October 1913) been assured by William II of Germany’s support if Austria-Hungary should start a preventive war against Serbia. This assurance was confirmed in the week following the assassination, before William, on July 6, set off upon his annual cruise to the North Cape, off Norway.
Austrian archduke Franz Ferdinand and his wife, Sophie, riding in an open carriage at Sarajevo …Henry Guttmann—Hulton Archive/Getty Images
The Austrians decided to present an unacceptable ultimatum to Serbia and then to declare war, relying on Germany to deter Russia
from intervention. Though the terms of the ultimatum were finally
approved on July 19, its delivery was postponed to the evening of July
23, since by that time the French president, Raymond Poincaré, and his premier, René Viviani,
who had set off on a state visit to Russia on July 15, would be on
their way home and therefore unable to concert an immediate reaction
with their Russian allies. When the delivery was announced, on July 24,
Russia declared that Austria-Hungary must not be allowed to crush
Serbia.
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Serbia replied to the
ultimatum on July 25, accepting most of its demands but protesting
against two of them—namely, that Serbian officials (unnamed) should be
dismissed at Austria-Hungary’s behest and that Austro-Hungarian
officials should take part, on Serbian soil, in proceedings against
organizations hostile to Austria-Hungary. Though Serbia offered to
submit the issue to international arbitration, Austria-Hungary promptly
severed diplomatic relations and ordered partial mobilization.
Home from his cruise on
July 27, William learned on July 28 how Serbia had replied to the
ultimatum. At once he instructed the German Foreign Office to tell
Austria-Hungary that there was no longer any justification for war and
that it should content itself with a temporary occupation of Belgrade.
But, meanwhile, the German Foreign Office had been giving such
encouragement to Berchtold that already on July 27 he had persuaded
Franz Joseph to authorize war against Serbia. War was in fact declared
on July 28, and Austro-Hungarian artillery began to bombard Belgrade the
next day. Russia then ordered partial mobilization against
Austria-Hungary, and on July 30, when Austria-Hungary was riposting
conventionally with an order of mobilization on its Russian frontier,
Russia ordered general mobilization. Germany, which since July 28 had
still been hoping, in disregard of earlier warning hints from Great
Britain, that Austria-Hungary’s war against Serbia could be “localized”
to the Balkans, was now disillusioned insofar as eastern Europe was
concerned. On July 31 Germany sent a 24-hour ultimatum requiring Russia
to halt its mobilization and an 18-hour ultimatum requiring France to promise neutrality in the event of war between Russia and Germany.
Both Russia and France predictably ignored these demands. On August
1 Germany ordered general mobilization and declared war against Russia,
and France likewise ordered general mobilization. The next day Germany
sent troops into Luxembourg and demanded from Belgium free passage for German troops across its neutral territory. On August 3 Germany declared war against France.
In the night of August 3–4 German forces invaded Belgium. Thereupon, Great Britain,
which had no concern with Serbia and no express obligation to fight
either for Russia or for France but was expressly committed to defend
Belgium, on August 4 declared war against Germany.
Austria-Hungary declared war against Russia on August 5; Serbia against Germany on August 6; Montenegro
against Austria-Hungary on August 7 and against Germany on August 12;
France and Great Britain against Austria-Hungary on August 10 and on
August 12, respectively; Japan against Germany on August 23; Austria-Hungary against Japan on August 25 and against Belgium
Romania had renewed its secret anti-Russian alliance of 1883 with the Central Powers on February 26, 1914, but now chose to remain neutral. Italy had confirmed the Triple Alliance
on December 7, 1912, but could now propound formal arguments for
disregarding it: first, Italy was not obliged to support its allies in a
war of aggression; second, the original treaty of 1882 had stated
expressly that the alliance was not against England.
On September 5, 1914, Russia, France, and Great Britain concluded the Treaty of London, each promising not to make a separate peace with the Central Powers. Thenceforth, they could be called the Allied, or Entente, powers, or simply the Allies.
The
outbreak of war in August 1914 was generally greeted with confidence
and jubilation by the peoples of Europe, among whom it inspired a wave
of patriotic feeling and celebration. Few people imagined how long or
how disastrous a war between the great nations of Europe could be, and
most believed that their country’s side would be victorious within a
matter of months. The war was welcomed either patriotically, as a
defensive one imposed by national necessity, or idealistically, as one
for upholding right against might, the sanctity of treaties, and
international morality.
