Assassination at Sarajevo
Heir to the Austro-Hungarian throne, Archduke Franz Ferdinand favoured the reorganisation of Austria-Hungary to create a third kingdom of Croatia. After the Austrian annexation of Bosnia and Hercegovina in 1908, Archduke Franz Ferdinand was assassinated. Serbian nationalist Gavrilo Princip shot, Ferdinand and his wife in the Bosnian town of Sarajevo on 28 June, 1914.
On July 23 the enraged Austrian government submitted an ultimatum to Serbia demanding punishment for the nationalists and further concessions. Serbia accepted most of the demands on 25 July, but Austria declared that the Serbian reply was unsatisfactory. The Russians then attempted to persuade Austria to change the terms of the ultimatum, declaring that if Austria marched on Serbia, Russia would mobilise their huge, but inefficient, army against Austria.
Refusing to submit the disputed terms to international arbitration, on 28 July, Austria-Hungary declared war on Serbia. Russia went to war on 1 August, determined to prevent further Austro-Hungarian encroachment in the Balkans. Russia's ally, France, then began to mobilise, prompting Germany, feeling trapped between the Russian and French armies, to declare war against France on 3 August. Germany tried to gain an advantage by striking first attacking France through neutral Belgium in accordance with the rigid war plan devised by Alfred von Schlieffen.
The French anticipated a brief conflict in which they could recover both the territory (Alsace-Lorraine) and prestige lost in 1871. Britain was not bound by the entente to enter the conflict; the entente powers did not form military alliances until after the outbreak of the war. The British government decided that it must honour its commitment to defend Belgian neutrality declaring war on Germany on August 4, and joining its French and Russian allies. Within two days Austria-Hungary had declared war against Russia. Italy temporarily remained neutral, claiming that its obligations to the Triple Alliance were void because Austria had initiated the war.
After the initial German attack had faltered, a war of attrition developed. To maintain their positions both sides dug trenches and soon two fortified lines running from the English Channel to Switzerland scarred Europe.
Essentially international tension during the pre-war years and aggressive nationalism initiated the conflict. The imprudent acts of governments in the final days of peace precipitated the bloodiest and costliest war that human history had yet witnessed. Then called "The Great War," it quickly involved all the great powers of Europe and eventually most countries of the world, and cost the lives of more than eight million soldiers.
The application of science made warfare more deadly than ever before; poison gas was tried, and the 'horrible efficiency of the new machine gun was proven. The first tanks were deployed and early submarines very nearly forced Britain out of the conflict. War in the air became established although the contribution of the rigid, lighter-than-air dirigible balloon, or airship, and the heavier-than-air airplane was not significant to the overall result.
Britain lost the large part of a generation of young men in World War I.