 Complete the following phrase:  He subsequently commanded the grenadier regiment, and in 1873 the 1st Brigade, 2nd Division, of the cavalry of the Imperial Guard. Although he took part in the Crimean War, being stationed at Belbek, his claim to distinction is due to his service in the Turkish war of 1877. He 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 attacked 