The Crimean War was a military conflict fought from October 1853 to February 1856 in which Russia lost to an alliance made up of the Ottoman Empire, the United Kingdom, Sardinia and France. The immediate cause of the war involved the rights of Christian minorities in the Holy Land, which was a part of the Ottoman Empire. The French promoted the rights of Roman Catholics, while Russia promoted those of the Eastern Orthodox Church. The longer-term causes involved the decline of the Ottoman Empire and the unwillingness of Britain and France to allow Russia to gain territory and power at the Ottoman Empire’s expense. It has widely been noted that the causes, in one case involving an argument over the keys to the Church of the Nativity, revealed a “great confusion of purpose”, yet they led to a war noted for its “notoriously incompetent international butchery”.

https://en.m.wikipedia.org/wiki/Crimean_War