At the beginning of 50s years, the situation in the Near East again aggravated. The main reason of the conflict was the collision of colonial interests of Russia, England, Russia and France, and also Russia and Austria in Near East and the Balkan. The position of Turkey was determined by its hopes for returning of Crimea and Caucasus, and also the restoration of its influence on the Balkans, which were actively supported by England and France.
Aspiring to finish with Turkey, the imperial government expected a friendly neutrality of Austria and Prussia, the international isolation of France, and hoped to agree with England. However Nikolay's I negociations with the English government had a boomerang effect: they promoted the Anglo-French rapprochement in the Eastern question.
The immediate cause of the war was the dispute between Catholic and orthodox churches for the right of possession of sacred places in Palestine. The dispute "about keys" developed into the Russian-French diplomatic conflict. In February 1853, prince A.S.Menshikov, the great-grandson and favorite of Peter, went to Turkish sultan as the Ambassador Extraordinary and Plenipotentiary, and demanded not only the recognition of the priority of Orthodox church above relics of Christianity, but also the conclusion of the convention on protection of the Russian king all over the Orthodox citizens of Turkey. Russia used the fact that the Sultan refused from these conditions, to break diplomatic relations with Turkey, and in May 1853, and June 1853, occupied the principalities of Danube. The 4th (16th) of October 1853, the Turkish sultan began military actions in Danube and in Transcaucasia. The 20th of October (the 1st of November) 1853, the formal announcement by Russia of war against Turkey 1853 followed.
War naked the backwardness of Russia and the weakness of its industry. 96% of the Russian infantrymen were armed with old smooth-bore silicon guns while in the French army, 33% of the soldiers had cut long-range rifles, and in the English army, 50%. The same situation was in artillery. The steam fleet of allies was 10 times more than the Russian one. In Russia there were 115 ships, including 24 steamships, and the allies had 454 ships, including 258 steamships.
In the first period of war (Russian-Turkish campaign in the Danube front and in Caucasus from October 1853 till April 1854), Russia, despite of its significant numerical advantage on Turkish forces, was able to achieve significant successes.
After number of diplomatic and military demarches, England and France declared war to Russia (March 1854), and Prussia and Austria took upon Russia a position of hostile neutrality, having demanded to remove the siege of Silistry and to clear the Danube princedoms. Nikolay I was obliged to accept these concessions. Russia appeared in the international isolation.
During the second period of the Crimean war (from April 1854 till February 1856) Russia was faced the powerful Anglo-French-Turkish coalition (in January 1855 the Sardinian kingdom joined it). In the spring and summer of 1854, the fleet of allies undertook a number of demonstrative attacks in the Baltic, Black and White seas, and also in the Far East, having attacked Russian fortresses. Facing resistance, allies during the autumn concentrated their efforts to control Crimea. The mistakes of the Russian command allowed allies to land a 62-thousand landing near Evpatoria and to start approach to Sevastopol. The 35-thousand Russian Crimean army under the command of admiral and general-aide-de-camp, naval minister A.S.Menshikov, who had neither abilities of the naval commander, nor talent of the commander, tried to stop the opponent on the River Alma.
During the battle of the 8th September, Russia was defeated and receded in the direction of Sevastopol, and then, after leaving a fortress for the care of its garrison and sailors, left to Bakhchisarai. In October 1854, Menshikov lost two more battles (under Balaklava and in the Inker-Mansky heights) and already near his resignation in February 1855, he did not undertake any resolute actions. The heroic defense of Sevastopol began on the 13th of September 1854 and had lasted for 11 months. 35 thousand defense counsels of the fortress, basically sailors, put out of action almost 70 thousand soldiers and officers of the allies. Not daring to storm the city, opponents were subjected to its five massive bombardments during many days. Sevastopolers sustained huge losses. The 27th of August 1855, the Russian parts could occupy the southern part of Sevastopol, after that it became impossible to protect Russian positions. The rest of the garrison abandoned the fortress.
During the campaign of the summer of 1854, the Caucasian front was rather successful for the Russian army: in several battles it stopped the progress of the Turkish army and repulsed the approach of the mountaineers of Imam Shamil on Kahety. During the autumn of 1855, the new approach of the Turkish and Greek army was broken, and the powerful fortress of Kare was taken. The forces of the two sides exhausted.
The 18th (30th) of 1856 in Paris, France and England signed a peace treaty for the benefit of Russia. All won territories were subject to exchange (Russia returned Kars and received back Sevastopol and other Russian cities); The Black sea became a neutral zone. Russia lost the right to have on the Black sea a military fleet and coastal arsenals; Russia also lost the estuary of Danube and the southern Bessarabia; its protectorate above Moldova and Walachia was cancelled, and also the right of protection of Serbia and the protection of the interests of the Orthodox population in Turkey. Thus, Russia lost its positions in the Near East and in the Balkans.