Peace has reigned in the Caucasus for thirteen years since the Treaty of Gulistan concluded the previous Russo-Persian War in 1813.

However, Fath 'Ali Shah, constantly in need of foreign subsidies, relies on the advice of British agents, who press him to reconquer the territories lost to Russia and pledge their support to military action.

The matter is decided in spring 1826, when a bellicose party of the Crown Prince, Abbas Mirza, prevails in Tehran and the Russian minister, Aleksandr Sergeyevich Menshikov, is placed under house arrest.

Lord Palmerston and other British leaders had expressed fears of Russian encroachment upon India and Afghanistan in the 1840s, and in the 1850s find a pretext for countering the Russian threat in the cause of protecting Roman Catholic holy places in Palestine.

France, under treaties negotiated during the eighteenth century, is the guardian of Roman Catholics in the Ottoman Empire, while Russia is the protector of Orthodox Christians.

For several years, however, Catholic and Orthodox monks have disputed possession of the Church of the Nativity in Bethlehem and the Church of the Holy Sepulchre in Jerusalem.

During the early 1850s, the two sides make demands that Ottoman sultan Abdülmecid cannot possibly satisfy simultaneously.

The sultan adjudicates in favor of the French in 1853, despite the vehement protestations of the local Orthodox monks.

Russia’s Tsar Nicholas dispatches Prince Aleksandr Sergeyevich Menshikov on a special mission to the Sublime Porte.

Previous treaties have committed the sultan "to protect the Christian religion and its Churches," but Menshikov attempts to negotiate a new treaty, under which Russia would be allowed to interfere whenever it deemed the Sultan's protection inadequate.

At the same time, however, the British government of Prime Minister Aberdeen dispatches Lord Stratford, ambassador to the Porte for the past decade, who learns of Menshikov's demands upon arriving in Istanbul.

Stratford applies his diplomatic skills to convince the Sultan to reject the treaty, which would compromise the independence of the Turks.

The Danube campaign opens when the Russians occupy the Danubian Principalities of Moldavia and Wallachia in May 1853, bringing their forces to the north bank of the River Danube.

In response, the Ottoman Empire also moves its forces up to the river, establishing strongholds at Vidin in the west and Silistra in the east, near the mouth of the Danube.

The Ottoman move up the River Danube is also of concern to the Austrians, who move forces into Transylvania in response.

However, the Austrians have begun to fear the Russians more than the Turks.

Indeed, like the British, the Austrians are now coming to see that an intact Ottoman Empire is necessary as a bulwark against the Russians.

Accordingly, Austria resists Russian diplomatic attempts to join the war on the Russian side and will remain neutral in the Crimean War.

Tsar Nicholas, shortly after learning of the failure of Aleksandr Sergeyevich Menshikov's diplomacy, and using the Sultan's failure to resolve the issue of the Holy Places as a pretext, orders his armies into the Ottoman principalities of Moldavia and Wallachia, in which Russia is the acknowledged special guardian of the Orthodox Church.

Nicholas believes that the European powers will not object strongly to the annexation of a few neighboring Ottoman provinces, especially given Russian involvement in suppressing the Revolutions of 1848.