Russia withdraws from Wallachia and Moldavia in 1851 but returns yet again in the summer of 1853, thus precipitating the Crimean War.

In 1854 Franz Joseph and the sultan force Tsar Nicholas I to withdraw his troops from the principalities, and imperial and Ottoman soldiers soon occupy them.

Russia's defeat in the Crimea forces the tsar to seek peace, affirmed in 1856 by the Treaty of Paris.

De jure Ottoman suzerainty over the principalities continues after the treaty, which abolishes the Russian protectorate and replaces it with a joint European guarantee.

The treaty also frees navigation on the Danube and forces Russia to cede part of southern Bessarabia, which includes control of the river's mouth, to Moldavia.