The Russo-Turkish War of 1828-1829 was fought between the Russian Empire and the Ottoman Empire from 1828 to 1829, resulting in the Russian occupation of the Danubian Principalities.
In 1827, Britain, France, and Russia decided to intervene jointly in the Greek War of Independence on the side of the Christian Greek rebels as the Ottomans and Egyptians threatened to overwhelm them. In response to the Imperial Russian Navy's participation in the October 1827 Battle of Navarino, the Ottoman sultan Mahmud II closed the Dardanelles to Russian ships and declared war on the Russian Empire. In April and May 1828, Prince Peter Wittgenstein invaded the Danubian Principalities, clearing the way for Czar Nicholas I of Russia to cross the Danube and advance into Dobruja that June. The Russians besieged the Ottoman citadels of Shumen, Varna, and Silistra in Bulgaria, taking Varna on 29 September. However, disease and exhaustion forced the Russians to retreat to Moldavia with heavy losses before they could take Shumen and Silistra. During the winter of 1828-1829, Wittgenstein withdrew to Bessarabia, resulting in Nicholas replacing him with the more energetic Hans Karl von Diebitsch. In May 1829, Diebitsch crossed the Danube and resumed the siege of Silistra. A 40,000-strong Ottoman relief army bound for Varna was defeated at the Battle of Kulevicha on 30 May 1829, and, three weeks later, Silistra fell to the Russians. On 2 July, the Russians launched their first offensive into the Balkans, with 35,000 Russians marching on Istanbul. The Russians captured Burgas before routing a Turkish army at Sliven on 31 July. On 22 August, the Russians took Adrianople, causing the Muslim population to flee the city. Meanwhile, the Russians tied down Turkish forces in the Caucasus and attacked Ottoman Black Sea fortresses that aided the Circassians. The Russians captured Kars in June 1828, Akhalkalaki in July, and Erzurum in June 1829. The Russian general Ivan Burstov advanced towards the port of Trebizond before being killed at Hart in July 1829, and the Russian general Ivan Paskevich responded by destroying the town.
On 2 September 1829, a peace treaty was signed between the Russians and Turks. Russia kept the ports of Anapa and Poti and the border forts of Atskhur, Akhalkalaki and Akhaltsikhe while returning its other Caucasian and Anatolian conquests. 90,000 Armenians migrated from Turkish to Russian territory after the peace. Russia now had access to most of the eastern shore of the Black Sea and the mouth of the Danube, Serbia achieved autonomy, and Russia was able to occupy Moldavia and Wallachia until Turkey had paid a large indemnity; they remained Russian protectorates until the Crimean War.