For centuries the Christian communities of Ottoman Palestine had contested the custody of the Church of the Holy Sepulchre in Jerusalem and the Church of the Nativity in Bethlehem, and the contest was minutely physical: which clergy held which keys, who might repair which roof, who processed at which hour, and where a silver star bearing a Latin inscription lay in the grotto at Bethlehem. That star disappeared in 1847, and the argument over its replacement became the immediate occasion of a European war.
Behind the clergy stood two treaties and two empires. France claimed a protectorate over Latin Christians from the capitulations granted by the sultans, most influentially those of 1740; Russia claimed a standing in Ottoman Orthodox affairs which it read into the treaty of Kuchuk Kaynarca of 1774. Napoleon III, needing Catholic support at home, pressed the Latin claims from 1850, and in 1852 the sultan issued a firman conceding several of them. Nicholas I, who understood himself as the protector of Orthodoxy and the heir of a Christian empire lost in 1453, sent Prince Menshikov to Constantinople in 1853 to demand not only the reversal of that concession but a treaty right of protection over some twelve million Orthodox subjects of the sultan.
Orlando Figes has argued that the war cannot be understood without taking that religious language seriously rather than treating it as a pretext for a quarrel about the straits. The Porte refused, Russia occupied the Danubian principalities, and by March 1854 Britain and France were at war with Russia.