Complex sentence: After considerable successes in both wars, Russia resumed the activity in the Caucasus, again met with resistance, notably led by Ghazi Mollah, Gamzat-bek and Hadji Murad.
Split into simpler sentences: After considerable successes in both wars, Russia resumed fighting in the Caucasus. They were again met with resistance, notably led by Ghazi Mollah, Gamzat-bek and Hadji Murad.