Russo-Turkish War (1828–1829) in the context of Janissary Corps

The Danubian Principalities (German: Donaufürstentümer, Russian: Дунайские княжества, Romanian: Principatele Dunărene) was a geopolitical term used for the Ottoman vassal principalities of Moldavia and Wallachia in the period of 1774–1858, a time of when the territories were a battleground between the Ottoman Empire, Habsburg Monarchy, and Russian Empire. While Russia returned Moldavia and Wallachia to the Ottoman Empire with the Treaty of Küçük Kaynarca (1774), it retained protectorship over the two and also of the Orthodox subjects in all of the Ottoman Empire. This made the two principalities have the status of dual authority, under Ottoman suzerainty but with Russian protection. The Russo-Turkish War (1828–1829) ended with the Russian occupation of the two principalities. The negotiations of the Great Powers in the aftermath of Russian defeat resulted in the unification of Moldavia and Wallachia in 1859.

Mahmud II (Ottoman Turkish: محمود ثانى, romanized: Maḥmûd-u s̠ânî, Turkish: II. Mahmud; 20 July 1785 – 1 July 1839) was the sultan of the Ottoman Empire from 1808 until his death in 1839. Often described as the "Peter the Great of Turkey", Mahmud instituted extensive administrative, military, and fiscal reforms. His disbandment of the conservative Janissary Corps removed a major obstacle to his and his successors' reforms in the Empire, creating the foundations of the subsequent Tanzimat era. Mahmud's reign was also marked by further Ottoman military defeats and loss of territory as a result of nationalist uprisings and European intervention.

Mahmud ascended the throne following an 1808 coup that deposed his half-brother Mustafa IV. Early in his reign, the Ottoman Empire ceded Bessarabia to Russia at the end of the 1806–1812 Russo-Turkish War. Greece waged a successful war of independence that started in 1821 with British, French and Russian support, and Mahmud was forced to recognize the independent Greek state in 1832. The Ottomans lost more territory to Russia after the Russo-Turkish War of 1828–1829, and Ottoman Algeria was conquered by France beginning in 1830.

The Akkerman Convention was a treaty signed on October 7, 1826, between the Russian and the Ottoman Empires in the Budjak citadel of Akkerman (present-day Bilhorod-Dnistrovskyi, Ukraine). It imposed that the hospodars of Moldavia and Wallachia be elected by their respective Divans for seven-year terms, with the approval of both Powers. It also provided for the retreat of Ottoman forces from both Danubian Principalities after their prolonged stay following military actions in 1821 (that were carried in response to the Filiki Etaireía in the Greek War of Independence), and Tudor Vladimirescu's uprising. The Ottomans also agreed to cede to Wallachia the control over the Danube ports of Giurgiu, Brăila and Turnu. The convention also tackled the Serbian question: in article 5, autonomy for the Principality of Serbia was given, and the return of lands removed in 1813. Serbs were also granted freedom of movement through the Ottoman Empire.

Sultan Mahmud II's repudiation of the convention triggered the Russo-Turkish War (1828–1829).