World War I
, 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.
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
.
The last surviving veterans of World War I were American serviceman
Frank Buckles
(died in February 2011), British-born Australian serviceman Claude Choules (died in May 2011), and British servicewoman
Florence Green
(died in February 2012), the last surviving veteran of the war.
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 Dimitrijevi?
, 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 Pa?i?
, 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.
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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 Hotzendorf
, 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
.
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 Poincare
, and his premier,
Rene 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 on August 28.
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
.