At the start of hostilities the Russian army of 100,000 men was commanded by Emperor Nicholas I, while the Ottoman forces were commanded by
Hussein Pasha. In April and May 1828 the Russian commander-in-chief, Prince Peter Wittgenstein, moved into Romanian Principates Wallachia and Moldavia. In June 1828, the main Russian forces under the emperor crossed the Danube and advanced into Dobruja.
The Russians then laid prolonged sieges to three key Ottoman citadels in modern Bulgaria: Shumla, Varna, and Silistra. With the support of the Black Sea Fleet under Aleksey Greig, Varna was captured on 29 September. The siege of Shumla proved much more problematic, as the 40,000-strong Ottoman garrison outnumbered the Russian forces. As the latter were harassed by Turkish troops and ill-equipped, many of its soldiers died of disease or exhaustion. The campaign turned to be an embarrassing one for Russia, considered a great military power, as its troops had to withdraw to Moldavia with heavy losses without having captured Shumla and Silistra.