Alexander the Great
After solidifying his rule over Macedonia and Greece, in the Spring of 334 B.C., Alexander the great sought to get revenge on Persia for their attacks on Greece. The battle of Granicus began against King Darius' armies along the banks of the Granicus river. Alexander the Great won this battle by a landslide, and all of western Asia minor seemed to lay at his feet.
Encouraged by his first defeat against Persia, Alexander the Great moved southwards towards Ionia to free Greek citites from the Persians and to secure the coast of Asia minor. Then Alexander moved further south towards Lybia. It was then, in the year 333 B.C., that Alexander sprung into action once more and met Darius at a mountain pass in Issus. It was there that the battle of Issus started. Alexander went straight for Darius, and when Darius fled, the Persian army was left in disarray. Darius left his wife and children, who were captured by Alexander but treated with respect, due to royalty. Alexander the Great also won this battle, but knew that there was more to come since there were still Persian provinces to the east.
In the summer of 331 B.C., Alexander and his army headed northeast through Syria to capture Babylon. Alexander captured some of Darius' men and interrogated them. This gave Alexander useful information and caused his to change his route more than once. This battle was called the battle of Guagamela, and it was fought in the Persian village of Guagamela. Thought Alexander's army was outnumber, he found a gap in the Persian army's setup and charged his army right through it. Darius sounded retreat and began to withdraw. Alexander won this battle, but Darius managed to get away. Alexander the Great pursued Darius for hundreds of miles. When he finally caught up to him, Darius was dead in his coach. Alexander had the assassins executed and gave Kind Darius I a royal funeral. After This victory, the Persian empire was split in two. With no rulers, and no one fighting for the Persian cause, Alexander could call himself king of the Persian empire.