Crimean War, 1853–56, a conflict between Russia on one side and the Ottoman Empire, Great Britain, France, and Sardinia on the other. The war ended Russian expansion in southeastern Europe and altered the balance of power in Europe.
Since the 17th century, Russia and the Ottoman Empire had been involved in a series of conflicts caused by Russian expansion into Ottoman lands. By the 1850's, France and Great Britain had become alarmed at the extent of Russia's advance into Turkish territories and the possible breakup of the Ottoman Empire. Under the pretext of exercising its right (which it had held since 1774) to protect all Orthodox Christians under Ottoman rule, Russia occupied the Ottoman provinces of Walachia and Moldavia in 1853. Czar Nicholas I later offered to withdraw Russian forces from the provinces but insisted on keeping the right to protect Orthodox Christians. The Turks rejected the czar's offer and declared war on Russia in October, 1853.
In March, 1854, after the Russians had defeated a Turkish naval squadron on the Black Sea, the British and the French entered the war on the side of Turkey to prevent Russia from gaining control of the Bosporus and the Dardanelles. Sardinia entered the war in January, 1855.
Meanwhile, British and French forces landed in the Crimea, in September, 1854. Shortly after landing, the allied armies defeated a Russian army near the Alma River. The Russians retreated to Sevastopol and the allies laid siege to the city. The siege led to battles at Balaklava and Inkerman; the Russians were defeated in both. A heroic but pointless charge against Russian artillery by British cavalry at Balaklava became famous as "the charge of the light brigade." During the course of the war, Florence Nightingale, a British nurse, gained worldwide attention for her untiring care of sick and wounded soldiers.
After being under siege for nearly a year, Sevastopol fell in September, 1855. Shortly afterward, the Russians sued for peace. In March, 1856, the war was formally ended by the Treaty of Paris.