Because of the decay of the once-great Islamic state, the Ottoman Empire, the foreign affairs of many of the powers of Europe around 1853 were consumed with the exact manner of its division so as not to result in
any imbalances of power. Tsar Nicholas I of Russia made an attempt to come to some sort of understanding with England with regard to that in 1853, partially to prevent any possible alliances against themselves by trying
to complicate relations between England and France and partially to secure a trade outlet through the Black Sea. Russia suggested that Moldavia and Wallachia (modern day Rumania), and Bulgaria be independent, that Serbia
become a sort of protectorate of the Russians, that Crete and Egypt be ceded to England, and that the Austrians be allowed to establish themselves on the Adriatic Sea. The English foreign minister rejected the offer and said that he was going to go talk with France about the whole
thing, which was no good for the Russians, since they liked France even less than they liked England. All the same, though, Nicholas I thought that something had been settled, and spoke with the British ambassador to St. Petersburg as though something had been. The assumptions that he made
during these conversations with regard to Russian intentions concerning the straits of the Dardanelles and the Bosporus, next to Constantinople, set off a storm of
bad P.R. for Russia in Britain.
This couldn't have come at much worse a time for the Russians, since they were having a dispute with the Ottomans and France at about the same time. It seems that the ruler of the Ottoman Empire had given rights of protection of various Christian churches in Palestine out to a number of
different nations, among them France and Russia. France was led by Napoleon III during this time, and he relied heavily on the support of domestic militant Christian groups to maintain his power base. In order to appease these groups,
France began in about 1840 to demand the return of some rights that they had lost in 1740, namely the key to the Church of the Nativity in old Jerusalem and the right to place a silver star on the birthplace of Jesus
in Bethlehem. The French were quite insistent about this and threatened the Ottomans with military action if they failed to comply. The Russians did not want the French to recover these rights, though, and told the Ottomans that if they gave in to the French that Russia would invade the
regions of Moldavia and Wallachia, presumably under Ottoman control at the time. The Ottomans were very weak and tried to appease everyone by adopting the smile and nod tactic whenever anyone said anything. This tactic wound up failing when it was discovered that the Ottomans pretty much had no
intention of giving anything to anybody. From there it was just a matter of who could move their military first, and the French did by sending warships to both the Ottoman capitol of Constantinople and the Bay of Tripoli. The ruler of
the Ottomans had no choice but to give in to the French, since they were the ones with the immediate threat looming over him.
When the Russians did respond to this maneuver, it was not with weapons, but with diplomacy. They sent an ambassador by the name of Menshikov to Constantinople. He demanded full restoration of rights to Greeks, a secret alliance with Russia, and protection under the Ottomans
of everyone in their empire who subscribed to any sort of Orthodox Christian faith. These were all relatively major commitments alone, and were really not received very well at all by the Ottomans, who were also apparently influenced against the Russians by a British ambassador by the name of Stratford de
Redcliffe. The Greek rights were ceded, but the Russians got none of their other demands. This diplomatic mission helped to strengthen the anti-Russian sentiment in the British parliament, though, and when the British
asked the French if they wouldn't mind helping eliminate Russian influence in the area, France said, "Okay."
A naval force from the two nations was dispatched to the Dardanelles in July 1853, whereupon Russia made good on its promise to invade Moldavia and Wallachia in June. The Ottomans then declared war on Russia in October. The
Anglo-French fleet met with a certain amount of success, penetrating to the Bosporus by this time, but in November, the Ottoman navy was destroyed by the Russians in the Black Sea. While this was a military victory for the Russians, it was a public relations disaster. The press in France and
England became more and more violent in tone and exhortation until in January 1854 France, England, and the Ottomans entered into formal alliance against Russia, which was exactly what the Tsar had tried to avoid with his various diplomatic failures. It didn't matter to him for too much longer, however,
since he was replaced by Tsar Alexander II in February of 1855. Allied troops landed in Crimea in September of 1854 with the objective of capturing Sevastopol. In spite of enormous casualties on all sides, Russia held Sevastopol until September of 1855, fueling the perception of incompetence
of all concerned due primarily to the huge casualties.
In 1855, Sardinia joined the war on the side of the European-Ottoman alliance, mostly so that it could get in on the peace conference afterward. Prussia was neutral until approached by officially neutral but anti-Russian Austria with the idea of establishing a defensive
alliance. Although not formally allied to the European-Ottoman group, these two countries did join the rest in demanding Russian withdrawal from Moldavia and Wallachia. When Russia did withdraw, Austria rushed to occupy
the two territories, forcing the Russians to maintain a defensive posture. A peace conference had been underway in Vienna throughout the war, and it formulated a few peace proposals, such as a Russian protectorate over Wallachia, Moldavia, and Serbia, freedom of navigation on the Danube, a revision of the arrangement of 1841 regarding the straits near Constantinople, and a five-power protection of Christians in Turkey instead of a Russian monopoly. Russia resisted signing this agreement until the
Austrians gave him an ultimatum saying roughly, "Do it or we're going to war against you too." It has been said that this ultimatum was the real cause of the end of the war, although the fall of Sevastopol which is traditionally seen as the decisive blow is a much more dramatic way to end. The new British prime minister was not satisfied since he wanted Russia to be partially dismembered after the war, and he sort of got his wish, although France and the rest weren't as happy about it as he was. Russia had to give a hunk of southern Bessarabia to the Moldavians in order to ensure the Danube's navigability, and had to promise not to station any troops on the Aland Islands. Also, the Black Sea was made neutral and pretty much everyone involved made a solemn promise not to mess with Turkey anymore, since nothing good really ever seemed to come of it.
Source: http://mars.acnet.wnec.edu/~grempel/courses/russia/lectures/19crimeanwar.html