Xerxes I, son of Darius, assembled one of the largest ancient armies to conquer all of Greece, as his father had intended. While he won the initial Battle of Thermopylae against Sparta's smaller force, the Greek navy defeated Xerxes' fleet at Salamis, forcing his army to retreat.

1. 480 BC
 Darius' son, Xerxes I, attempted to finish what his father started
 wanted to conquer all of Greece
 Made one of the largest armies assembled during ancient times
 He initially won the Battle of Thermopylae against a much smaller army from
Sparta
 the Greek fleet defeated his navy at the Battle of Salamis
 Was then forced to retreat