From The Crimean War: A History, by Orlando Figes (Metropolitan, 2011), Kindle Loc. 260-275:
In August 1851 the French formed a joint commission with the Turks to discuss the issue of religious rights. The commission dragged on inconclusively as the Turks carefully weighed up the competing Greek and Latin claims. Before its work could be completed, La Valette proclaimed that the Latin right was ‘clearly established’, meaning that there was no need for the negotiations to go on. He talked of France ‘being justified in a recourse to extreme measures’ to support the Latin right, and boasted of ‘her superior naval forces in the Mediterranean’ as a means of enforcing French interests.
It is doubtful whether La Valette had the approval of Napoleon for such an explicit threat of war. Napoleon was not particularly interested in religion. He was ignorant about the details of the Holy Lands dispute, and basically defensive in the Middle East. But it is possible and perhaps even likely that Napoleon was happy for La Valette to provoke a crisis with Russia. He was keen to explore anything that would come between the three powers (Britain, Russia, Austria) that had isolated France from the Concert of Europe and subjected it to the ‘galling treaties’ of the 1815 settlement following the defeat of his uncle, Napoleon Bonaparte. Louis-Napoleon had reasonable grounds for hoping that a new system of alliances might emerge from the dispute in the Holy Lands: Austria was a Catholic country, and might be persuaded to side with France against Orthodox Russia, while Britain had its own imperial interests to defend against the Russians in the Near East. Whatever lay behind it, La Valette’s premeditated act of aggression infuriated the Tsar, who warned the Sultan that any recognition of the Latin claims would violate existing treaties between the Porte and Russia, forcing him to break off diplomatic relations with the Ottomans. This sudden turn of events alerted Britain, which had previously encouraged France to reach a compromise, but now had to prepare for the possibility of war.
The war would not actually begin for another two years, but when it did the conflagration it unleashed was fuelled by the religious passions that had been building over centuries.