Born c. 360 B.C., Crete
Died 312 B.C.

By the sixth century B.C., Persia had become the largest and strongest empire in the known world, presiding over Egypt and all of western Asia. Persian ruler Darius I (reigned 521–486 B.C.) decided to add Greece to his vast holdings, and a series of conflicts known as the Persian Wars took place in 500–449 B.C. between the Persian empire and the Greek city-states (self-ruling areas, each made up of a city and its surrounding territory). By the fourth century B.C., however, the Greeks had grown in military strength and Persia had weakened. The Greeks looked to avenge the earlier invasions and conquer the huge Persian empire.

Philip II of Macedon (reigned 359–336 B.C.), ruler of a kingdom in northern Greece, united the Greek city-states and prepared to attack Persia, now led by Darius III (reigned...