The Crimean War was fought from October 1853 to February 1856 between Russia 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 flashpoint was a disagreement over the rights of Christian minorities in Palestine, then part of the Ottoman Empire, with the French promoting the rights of Roman Catholics, and Russia promoting those of the Eastern Orthodox Church.

Crimean War - Wikipedia