He then made a series of successful reconnaissances of the Tundzha valley, cut the railway in two places, occupied Stara Zagora () and Nova Zagora (), checked the advance of Suleiman Pasha's army and returned again over the Balkans. In October he was appointed commander of the allied cavalry, and attacked the Plevna line of communication to Orhanie with a large mixed force, captured Gorni-Dubnik, Telish and Vratsa and, in the middle of November, Orhanie itself. Pleven was isolated, and after its liberation in December Gourko led his troops amidst snow and ice over the Balkans to the fertile valley beyond. He liberated Sofia and decisively defeated Suleiman Pasha at the Battle of Philippopolis and occupied Adrianople. The armistice at the end of January 1878 stopped further operations. With the help of Carol I of Romania and a few other Russian commanders such as : Michael Nikolaevich and Iosif Vladimirovich Gourko, the Russian Empire managed to break free Romania, Serbia and Montenegro. After a Russian victory the Treaty of Berlin was signed.