Russia expanded down the eastern and western shores of the Black Sea in the first half of the nineteenth century, hoping to eventually gain possession of Constantinople and the Turkish Straits. The decline of the Ottoman Empire seemed to favour these plans, but other European powers were also interested in controlling the Bosphorus.
Great Britain and France were unable to agree with Russia on spheres of influence in the Middle East. Wrongly believing that these two rivals would not join forces against him, Nicholas I moved his troops into Moldavia and Wallachia. But London and Paris jointly demanded a Russian withdrawal. When Nicholas ignored the ultimatum, Britain and France declared war in March 1854.
The Crimean War started off well for Russia. On 30 November 1853, Admiral Pavel Nakhimov destroyed a Turkish squadron at the Battle of Sinop. But Britain and France sent their navies to the Crimea in September 1854. The allied fleet landed an expeditionary force at Eupatoria and confined the Russian navy to its base at Sebastopole.
After defeating a Russian army at the Battle of Alma on 20 September, the Allies besieged Sebastopole on 17 October 1854. The city was captured on 9 September 1855, despite an heroic defence lasting almost a year. By this time, both sides were exhausted and there were no further military operations in the Crimea.
On 18 February 1855, Nicholas I died and was succeeded by his son, Alexander II, who signed the Treaty of Paris on 30 March 1856. Under the terms of the peace agreement, the Black Sea was turned into a demilitarised zone. This meant that Russia could not have a Black Sea Fleet, a humiliating setback which greatly diminished her influence in the area.