Complex sentence: He wanted to finish off business first with Byzantines and then reinforce the Muslim army at Yarmouk sending 6000 soldiers as a reinforcement in small bands which would give the impression of a continuous stream of reinforcements.
Split into simpler sentences: He wanted to finish off business first with the Byzantines and then reinforce the Muslim army at Yarmouk. He sent 6000 soldiers in small bands to give the impression of a continuous stream of reinforcements.