The Crimean War was fought between the Russian Empire and an alliance of the Ottoman Empire, the Second French Empire, the United Kingdom of Great Britain and Ireland, and the Kingdom of Sardinia-Piedmont from October 1853 to February 1856. Geopolitical causes of the war included the "Eastern question" (the decline of the Ottoman Empire), expansion of Imperial Russia 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 war's proximate cause was a dispute between France and Russia over the rights of Catholic and Orthodox minorities in Palestine. After the Sublime Porte refused Tsar Nicholas I's demand that the Empire's Orthodox subjects be placed under his protection, Russian troops occupied the Danubian Principalities in July 1853. The Ottomans declared war on Russia in October. Fearing the growth of Russian influence and compelled by public outrage over the annihilation of the Ottoman squadron at Sinop, Britain and France joined the war on the Ottoman side in March 1854. The Russian advance was halted at Silistria in June.