Battle of Siffin
Abbas debuted as a soldier in the Battle of Siffin, one of the main conflicts of the struggle between Abbas's father, Ali, and Muawiyah in 657. Wearing the clothes of his father, who was known to be a great warrior, Abbas killed many enemy soldiers. Muawiya's forces actually mistook him for Ali. Therefore, when Ali appeared on the battlefield, Muawiya's soldiers were astonished to see him and confused about the identity of the other soldier. Ali then introduced Abbas by saying: