This paper analyses the causes of the Crimean War of 1853-1856 through the prism of objective national interests and subjective motivations of rulers and leading statesmen. The issue will be examined on the basis of the positions of the main parties to the conflict — the Russian Empire and the Kingdom of Great Britain. By analyzing the position of Emperor Nicholas I on the eve of the Crimean War, the authors come to the conclusion that the main motives for entering the conflict were objective and subjective factors in their combination. On the one hand, Russia's main objectives were to ensure security and stability in Central Asia and to secure control of the Bosporus and Dardanelles straits through a friendly regime in the Ottoman Empire. However, the achievement of these aims was hampered by Nicholas's erroneous subjective perception of the international conjuncture of the time — the hope for Austrian and Prussian support and the misjudgment of the success of the negotiations with Aberdeen. In the nineteenth century Britain became increasingly involved in Middle Eastern affairs in the form of trade links with the Ottoman Empire and political support for the Sultan's rule. The defence of Turkey can be explained by the intention to limit the expansion of the Russian Empire, a rival in the region, which was at the crossroads of trade routes and served as a link to India. However, the perception of the Middle East as a vital region for Britain is primarily due to the views of Henry John Palmerston - Foreign Secretary and then British Prime Minister - who used political influence to argue for the importance of keeping the 'sick man of Europe' safe. Disagreements within the British cabinet just before the outbreak of war, as well as misunderstandings among British politicians about the intentions of Nicholas I, also led to the choice of a hardline strategy towards the Russian Empire and, as a consequence, Britain's entry into the war.