The Crimean War was a military conflict fought from October 1853 to February 1856 in which Russia lost to an alliance of France, the Ottoman Empire, the United Kingdom and Sardinia. The immediate cause of the war involved the rights of Christian minorities in the Holy Land, which was part of the Ottoman Empire. The French promoted the rights of Roman Catholics, and Russia promoted those of the Eastern Orthodox Church. Longer-term causes involved 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. It has widely been noted that the causes, in one case involving an argument over a key, had never revealed a "greater confusion of purpose" but led to a war that stood out for its "notoriously incompetent international butchery".
The churches worked out their differences with the Ottomans and came to an agreement, but both French Emperor Napoleon III and Russian Emperor Nicholas I refused to back down.