Complex sentence: After series of successes Albanian rebels managed to capture the city of Skopje, then administrative centre of Kosovo vilayet within Ottoman rule and even came near Thessaloniki, Ottoman Empire negotiators agreed to fulfill their demands.
Split into simpler sentences: After series of successes Albanian rebels managed to capture the city of Skopje, then administrative centre of Kosovo vilayet within Ottoman rule. After rebels came near Thessaloniki, Ottoman Empire negotiators agreed to fulfill their demands.