Complex sentence: The battle was still in its early stages when Meenas was killed; and as the news of his death spread among his men, the Byzantine soldiers went wild with fury and attacked savagely to avenge their beloved leader's death.
Split into simpler sentences: The battle was still in its early stages when Meenas was killed. As the news of his death spread among his men, the Byzantine soldiers went wild with fury and savagely attacked to avenge their beloved leader's death.