550- 469 BCE -- A series of battles and uprisings stemming from Persian encroachment into Greek territories. The Persians conquered the Ionian Greek cities prior to 550 BCE, however, the Persian rule was seen as needlessly harsh and cruel by the Greeks. The Greeks revolted in 499 BCE
and this lead to a series of battles that was not resolved with finality until 469 BCE, when the Greeks formed the Delian League and the largest Greek army ever. They were then able to defeat the Persian army and navy. One of the most important battles of this period was, Marathon, 490 BCE, where the Athenians and Plataeans defeated the Persians, lead by Darius who was attempting to expand the Persian empire onto mainland Greece.