Background of World War I

In the 19th century, the major European powers had gone to great lengths to maintain a balance of power throughout Europe, resulting by 1900 in a complex network of political and military alliances throughout the continent. These had started in 1815, with the Holy Alliance between Prussia, Russia, and Austria. Then, in October 1873, German Chancellor Bismarck negotiated the League of the Three Emperors (German: Dreikaiserbund) between the monarchs of Austria–Hungary, Russia and Germany. This agreement failed because Austria–Hungary and Russia could not agree over Balkan policy, leaving Germany and Austria–Hungary in an alliance formed in 1879, called the Dual Alliance. This was seen as a method of countering Russian influence in the Balkans as the Ottoman Empire continued to weaken. In 1882, this alliance was expanded to include Italy in what became the Triple Alliance.

After 1870, European conflict was averted largely due to a carefully planned network of treaties between the German Empire and the remainder of Europe orchestrated by Chancellor Bismarck. He especially worked to hold Russia at Germany's side to avoid a two-front war with France and Russia. With the ascension of Wilhelm II as German Emperor (Kaiser), Bismarck's system of alliances was gradually de-emphasized. For example, the Kaiser refused to renew the Reinsurance Treaty with Russia in 1890. Two years later the Franco-Russian Alliance was signed to counteract the force of the Triple Alliance. In 1904, the United Kingdom sealed an alliance with France, the Entente cordiale and in 1907, the United Kingdom and Russia signed the Anglo-Russian Convention. This system of interlocking bilateral agreements formed the Triple Entente.

German industrial and economic power had grown greatly after unification and the foundation of the empire in 1870. From the mid-1890s on, the government of Wilhelm II used this base to devote significant economic resources to building up the Imperial German Navy (German: Kaiserliche Marine), established by Admiral Alfred von Tirpitz, in rivalry with the British Royal Navy for world naval supremacy. As a result, both nations strove to out-build each other in terms of capital ships. With the launch of HMS Dreadnought in 1906, the British Empire expanded on its significant advantage over its German rivals. The arms race between Britain and Germany eventually extended to the rest of Europe, with all the major powers devoting their industrial base to the production of the equipment and weapons necessary for a pan-European conflict. Between 1908 and 1913, the military spending of the European powers increased by 50 percent.

Austria-Hungary precipitated the Bosnian crisis of 1908–1909 by officially annexing the former Ottoman territory of Bosnia Herzegovina, which it had occupied since 1878. This greatly angered the Pan-Slavic and thus pro-Serbian Romanov Dynasty who ruled Russia and the Kingdom of Serbia, because Bosnia Herzegovina contained a significant Slavic Serbian population. Russian political maneuvering in the region destabilized peace accords that were already fracturing in what was known as "the Powder keg of Europe".

In 1912 and 1913, the First Balkan War was fought between the Balkan League and the fracturing Ottoman Empire. The resulting Treaty of London further shrank the Ottoman Empire, creating an independent Albanian State while enlarging the territorial holdings of Bulgaria, Serbia, Montenegro and Greece. When Bulgaria attacked both Serbia and Greece on 16 June 1913 it lost most of Macedonia to Serbia and Greece and Southern Dobruja to Romania in the 33 day Second Balkan War, further destabilising the region.

On 28 June 1914, Gavrilo Princip, a Bosnian-Serb student and member of Young Bosnia, assassinated the heir to the Austro-Hungarian throne, Archduke Franz Ferdinand of Austria in Sarajevo, Bosnia. This began a period of diplomatic manoeuvring between Austria-Hungary, Germany, Russia, France and Britain called the July Crisis. Wanting to end Serbian interference in Bosnia conclusively, Austria-Hungary delivered the July Ultimatum to Serbia, a series of ten demands which were intentionally unacceptable, made with the intention of deliberately initiating a war with Serbia. When Serbia acceded to only eight of the ten demands levied against it in the ultimatum, Austria-Hungary declared war on Serbia on 28 July 1914. Strachan argues "Whether an equivocal and early response by Serbia would have made any difference to Austria-Hungary's behaviour must be doubtful. Franz Ferdinand was not the sort of personality who commanded popularity, and his demise did not cast the empire into deepest mourning".

The Russian Empire, unwilling to allow Austria–Hungary to eliminate its influence in the Balkans, and in support of its long time Serb proteges, ordered a partial mobilization one day later. When the German Empire began to mobilize on 30 July 1914, France, sporting significant animosity over the German conquest of Alsace-Lorraine during the Franco-Prussian War, ordered French mobilization on 1 August. Germany declared war on Russia on the same day. The United Kingdom declared war on Germany, on 4 August 1914, following an 'unsatisfactory reply' to the British ultimatum that Belgium must be kept neutral.
Background of World War I

Before World War II, the war was also known as The Great War, The World War, The Kaiser's War, The War of the Nations, The War in Europe, or The European War. In the United Kingdom and the United States it was commonly called The war to end war. In France and Belgium it was sometimes referred to as La Guerre du Droit (the War for Justice) or La Guerre Pour la Civilisation / de Oorlog tot de Beschaving (the War to Preserve Civilisation), especially on medals and commemorative monuments. The term used by official histories of the war in Britain and Canada is First World War, while American histories generally use the term World War I.

The earliest known use of the term First World War appeared during the war. German biologist and philosopher Ernst Haeckel wrote shortly after the start of the war:

There is no doubt that the course and character of the feared "European War" ... will become the first world war in the full sense of the word.

—The Indianapolis Star, 20 September 1914

The term was used again near the end of the war. English journalist Charles à Court Repington wrote:

I saw Major Johnstone, the Harvard Professor who is here to lay the bases of an American History. We discussed the right name of the war. I said that we called it now The War, but that this could not last. The Napoleonic War was The Great War. To call it The German War was too much flattery for the Boche. I suggested The World War as a shade better title, and finally we mutually agreed to call it The First World War in order to prevent the millennium folk from forgetting that the history of the world was the history of war.

—The First World War, 1914–1918 (1920), Volume I, Page 391.

World War I statistic

World War I
Clockwise from top: Trenches on the Western Front; a British Mark IV Tank crossing a trench; Royal Navy battleship HMS Irresistible sinking after striking a mine at the Battle of the Dardanelles; a Vickers machine gun crew with gas masks, and German Albatros D.III biplanes
Date 28 July 1914 – 11 November 1918 (Armistice) Treaty of Versailles signed 28 June 1919 Location Europe, Africa, the Middle East, and the Pacific Islands (briefly in China) Result Allied victory End of the German, Russian, Ottoman, and Austro-Hungarian empires Formation of new countries in Europe and the Middle East Transfer of German colonies and regions of the former Ottoman Empire to other powers Establishment of the League of Nations.
Belligerents
Allied (Entente) Powers France British Empire Russian Empire (1914–17) Italy (1915–18) United States (1917–18) Japan Romania (1916–18) Serbia Belgium Greece (1917–18) Portugal (1916–18) Montenegro (1914–16) and others	Central Powers German Empire Austria-Hungary Ottoman Empire Bulgaria (1915–18)
Commanders and leaders
Leaders and commanders Aristide Briand Georges Clemenceau Ferdinand Foch George V H.H. Asquith David Lloyd George Nicholas II Alexander Kerensky Antonio Salandra Vittorio Orlando Woodrow Wilson John Pershing Ferdinand I Peter I and others	Leaders and commanders Wilhelm II Paul von Hindenburg Erich Ludendorff Franz Joseph I Karl I Mehmed V İsmail Enver Ferdinand I and others
Strength
Allies 15,000,000 8,317,000 5,200,000 5,000,000+ 4,000,000 660,000 420,000 267,000 250,000 40,000+ 33,000 Total: 39,087,000+ (estimated)	Central Powers 13,000,000 7,800,000 2,000,000+ 1,200,000 Total: 24,000,000+ (estimated)
Casualties and losses
Military dead: 5,525,000 Military wounded: 12,831,500 Military missing: 4,121,000 Total: 22,477,500 KIA, WIA	Military dead: 4,386,000 Military wounded: 8,388,000 Military missing: 3,629,000 Total: 16,403,000 KIA, WIA