The Crimean War was fought from October 1853 to February 1856 between the Russian Empire and an ultimately victorious alliance of the Ottoman Empire, France, the United Kingdom and Sardinia-Piedmont. Geopolitical causes of the war included the decline of the Ottoman Empire, the expansion of the Russian Empire in the preceding Russo-Turkish Wars, and the British and French preference to preserve the Ottoman Empire to maintain the balance of power in the Concert of Europe.

The front settled into the siege of Sevastopol, involving brutal conditions for troops on both sides. Sevastopol finally fell after eleven months, after the French had assaulted Fort Malakoff. Isolated and facing a bleak prospect of invasion by the West if the war continued, Russia sued for peace in March 1856. France and Britain welcomed the development, owing to the conflict's domestic unpopularity.

The Treaty of Paris, signed on 30 March 1856, ended the war. It forbade Russia to base warships in the Black Sea. The Ottoman vassal states of Wallachia and Moldavia became largely independent. Christians in the Ottoman Empire gained a degree of official equality, and the Orthodox Church regained control of the Christian churches in dispute. The Crimean War marked a turning point for the Russian Empire. The war weakened the Imperial Russian Army, drained the treasury and undermined Russia's influence in Europe.