Complex sentence: In the campaigns of 962--963 by brilliant strategy he conquered the cities of Cilicia and advanced into Syria where he captured Aleppo in collusion with his nephew John Tzimiskes, but made no permanent conquests.
Split into simpler sentences: In the campaigns of 962--963, he employed brilliant strategy to conquer the cities of Cilicia and to advance into Syria. There he captured Aleppo, in collusion with his nephew, John Tzimiskes, but they made no permanent conquests.