On September 17, 1769, the Russians began their initial campaign over the Dniester into Moldavia. The elite Ottoman Janissaries took heavy casualties from the Russians at Khotyn but managed to hold on, and the remainder of the Ottoman army panicked and abandoned the field and the Russians claimed the fortress. With the Ottomans in disarray the Russians took the capital of Moldavia (Jassy) on October 7. They continued the advance south into Wallachia, occupying its capital Bucharest on November 17. From the capital of Bucharest, the Russians fanned out through the principality, only later being challenged by Grand Vizier Mehmed Emin Pasha at Kagul on Aug 1, 1770. The Russians routed the Grand Vizier's forces and allegedly one-third of the Ottoman troops drowned in the Danube trying to escape.