yarmuk

what if sassanids reinforced Byzantines in the middle of battle of Yarmuk as a friendly gesture to form an alliance will this surprise attack win the battle? will this cement an allaince and stop arabs ?

Heraclius is healthy and fit to command in 636, taking personal charge of the Byzantine army assembled against the Arab invasion force at the Yarmuk. He wisely chooses not to wait, reviving the spirit of his Persian campaign among his men, and smashes the Arab army first on the Yarmuk and then...