 Complete the following phrase:  Joining Russo-Turkish War of 18771878, he usually fought under Iosif Gurko, who led the spearhead of the Russian invasion, took Tarnovo on July 7, crossed the Balkans by the Haim Boaz passwhich debouches near Hainkyoiand, despite considerable resistance, captured Uflani, Maglizh and Kazanlak; on July 18 he participated attack on 