Complex sentence: In the next year, an Arab army under Maimun al-Gurgumani ("the Mardaite") marched against Tyana, but failed to take the city, while the defenders managed to trap and annihilate a detachment of the Arab army, killing Maimun himself.
Split into simpler sentences: In the next year, an Arab army under Maimun al-Gurgumani ("the Mardaite") marched against Tyana, but failed to fail the city. The defenders even managed to trap and annihilate a detachment of the Arab army, killing Maimun himself.