Complex sentence: After repulsing the Russian attacks, Osman failed to press his advantage and possibly drive off the besiegers; he did, however, make a cavalry sortie on 31 August that cost the Russian 1,300 casualties, and the Ottomans 1,000.
Split into simpler sentences: After repulsing the Russian attacks, Osman failed to press his advantage and possibly drive off the besiegers. He did, however, make a cavalry sortie on 31 August that cost the Russian 1,300 casualties and the Ottomans 1,000.