The First World War begins

The assassination at Sarajevo in June 1914 led Austria-Hungary to pressure Serbia. Ultimatums, mobilizations, and declarations spread the crisis during the following weeks. Alliance commitments and security calculations accelerated decisions. Germany invaded Belgium and France, Britain entered, and fighting developed in eastern Europe and the Balkans. Additional states joined over time, while colonies supplied soldiers and resources. A European diplomatic crisis became warfare across continents.

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Machine guns, artillery, and wire made attacks costly, producing prolonged trench warfare in the west. Railways, factories, finance, rationing, propaganda, and labour controls sustained operations. Submarines, blockade, and colonial campaigns affected inhabitants far from the main fronts. Women entered additional industrial employment, and civilians suffered hunger and displacement. Gas, aircraft, and tanks changed military practice without producing the quick victory that many participants had expected.

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Revolution in Russia, American participation, and domestic crises altered the balance before the armistice of 1918. Ottoman, Austro-Hungarian, German, and Russian imperial arrangements collapsed. New states and borders emerged. Peace treaties addressed reparations, territories, and international organization while leaving disputes about minorities, colonies, and security. Families, veterans, and damaged economies required prolonged reconstruction. The conflict entered political and cultural life through experiences that shaped an entire generation.

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