Complex sentence: The fortress was again stormed by the Russians in the Battle of Kars during the Russo-Turkish War, 1877-78 under generals Loris-Melikov and Ivan Lazarev and on its conclusion was transferred to Russia by the Treaty of San Stefano.
Split into simpler sentences: The fortress was again stormed by the Russians in the Battle of Kars during the Russo-Turkish War, 1877-78 under generals Loris-Melikov and Ivan Lazarev. Following the war, Kars was transferred to Russia by the Treaty of San Stefano.