19151923

1915–1923 refers to the period spanning the later years of World War I and the early interwar era. It encompasses major military campaigns, revolutions, and the redrawing of political boundaries that followed the war's end.

During 1915–1918, the Allied and Central powers fought across Europe, Africa, the Middle East, and the seas. Notable developments include Italy's entry into the war in 1915, the sustained battles of 1916 such as Verdun and the Somme, and the entry of the United States into the conflict in 1917, which helped shift momentum. The Russian Revolution of 1917 led to Russia's withdrawal from the war, while the Central Powers began negotiating peace. The Armistice of 11 November 1918 ended fighting, and the 1918–1919 influenza pandemic affected populations worldwide.

Postwar diplomacy culminated in a series of treaties. The Paris Peace Conference of 1919 produced the Treaty of Versailles and several other agreements that redrew borders and established new states and mandates. The League of Nations was founded to promote collective security, though its effectiveness varied. The period also saw the dissolution of empires and territorial realignments in Europe, the Middle East, and beyond, including new states in Central and Eastern Europe and the dissolution of the Austro-Hungarian and Ottoman Empires.

Politically, the era witnessed significant upheaval. Ireland established a self-governing dominion in 1922 following the Anglo-Irish Treaty, while in Italy, Benito Mussolini and the Fascist movement rose to power in 1922. In Germany, 1923 featured hyperinflation, the occupation of the Ruhr, and the Beer Hall Putsch, reflecting domestic instability. In Turkey, the Turkish War of Independence culminated in the 1923 Treaty of Lausanne, recognizing a modern Turkish state.

The 1915–1923 period shaped the interwar order and left a legacy of new borders, institutions, and political currents that influenced international relations throughout the 1920s and 1930s.