The Greek region of Ionia had been conquered by Persia around 540 BC and the city-states were ruled by Persian tyrants from then on. Darius I was a usurper, becoming the third king of the Persian Empire by overthrowing Gaumata through the assistance of six noble families, in September 522 BC. In 499 BC, the Greek city-states of Athens and Eritrea encouraged the Ionian Revolt against the Persians. The Ionians attacked and burned Sardis, and Darius responded by following them back to Ionia, defeating them in the Battle of Ephesus in 498 BC. The Persians then responded with a three-pronged attack in 497 BC, capturing the outlying areas of the rebellion. The forces stalemated in 496-495 BC when the Greeks consolidated into Caria. In 494 BC, the Persian army and navy regrouped and attacked Miletus directly. The Samians defected and the entire area came under Persian rule. The Persians spent 493 BC cleaning up the rest of the rebel outbreaks and imposed a peace settlement that was considered fair by all. The fallout, however, was a vow by Darius to punish Athens and Eritrea for instigating the revolt. This is a category of persian coins.
Darius saw the myriad of Greek city-states as unstable and a possible threat to his rule, so according to Herodotus, he decided to conquer all of Greece. In 492 BC, Darius invaded and showed the Greeks the strength of his forces. He sent messengers to each of the Greek city-states in 491 BC, asking for a gift of ‘earth and water’ as a token of their submission to Persia. Many of the city-states submitted, but the ambassadors to Athens were put on trial and then thrown in a pit, and the ones to Sparta were thrown in a well.
With Athens and Sparta clearly declaring war on Persia by murdering the envoys, the wheels were set in motion. Darius assembled forces led by Datis and Artaphernes and attacked Naxos in 490 BC. The other Cycladic Islands surrendered and the Persians moved on Eritrea, destroying it. Pushing onward, the Persians landed at the Bay of Marathon, heading toward Athens. The Athenians were ready, however, and defeated the Persians, forcing them to return to Asia.
Darius was not giving up so easily. He began assembling a massive army to utterly dominate Greece, but in 486 BC, the people under Persian rule in Egypt rebelled. Darius died while preparing to march on Egypt and the Persian throne passed to his son, Xerxes I. Xerxes quickly put Egypt back in line, then prepared for the full assault on Greece. Since this was expected to be a long, arduous war, Xerxes decided the Hellespont would have to be bridged in order to move his enormous number of forces. A canal was dug across the Isthmus of Mount Athos and by early 480 BC, the Persians were marching across two pontoon bridges to Europe.
The Athenians weren’t sitting around and waiting for the inevitable. In 482 BC, the Greeks decided to build a large fleet of triremes. Still, they did not have enough forces to fight on both land and sea. Xerxes followed in his father’s footsteps and sent ambassadors to all of the Greek city-states, except Athens and Sparta, asking for ‘earth and water’ as a token of their alliance. A congress of Greek city-state representatives met in Corinth in 481 BC to establish a confederate alliance to oppose the Persian invasion. The alliance representatives met again in Spring 480 BC to discuss strategy and after failing to realize the Persians could avoid their blockade at the Vale of Tempe, moved all of the forces to southern Greece. In order for Xerxes to advance, he would have to lead his troops through the narrow pass of Thermopylae to get to Boeotia, Attica and the Peloponnesus. As the Greeks were preparing for the assault, the women and children of Athens were evacuated to Peloponnesus-Troezen.
It took some months for the Persians to move through Thrace and Macedonia and when news arrived the enemy was near, it happened to be during the Olympic Games, so it would be sacrilegious for the Spartan army to be involved in war. King Leonidas I took with him 300 Spartans to hold off the Persians and wait for the rest of the army. Along the way, according to Herodotus, Leonidas gathered for reinforcements more than 7,000 troops:
Sparta: 300; Tegea: 500; Mantinea: 500; Arcadian Orchomenos: 120; Rest of Arcadia: 1000; Phlius: 200; Mycenae: 80; Corinth: 700; Thebes: 400; Phocia: 1000; and the rest from Opuntian Lokris.
Leonidas and his forces arrived at Thermopylae and the Persians arrived as well. The Greeks held a council of war and there was some disagreement of what to do. Leonidas calmed everyone by saying he would stay and defend the pass. Xerxes sent an emissary to negotiate with Leonidas, offering them the title “Friends of the Persian People”, along with land to re-settle that was better than what they have now. Leonidas refused. Another ambassador was sent on August 3, demanding Leonidas to “hand over his arms’ to which he famously replied, “come and take them”.
Xerxes waited for four days before attacking to let the Greeks self-destruct and disperse. On the fifth day, the 2.6+ million strong Persian forces attacked – and were held off. Toward the end of the second day of battle, a traitor named Ephialtes of Trachis, showed Xerxes a hidden goat path named the Anopaea Pass, which allowed the Persians to flank the Greeks.
Leonidas called a war council on the third day and decided to create a rear guard with his Spartans so the rest of the Greeks could escape. On August 9, 480 BC, Xerxes and the Persians defeated King Leonidas and the Spartan army at the Battle of Thermopylae, killing every last soldier who remained to fight. The movies 300 and 300: Rise of an Empire, are based on the events.
After Thermopylae, the Persians proceeded to burn and sack all of the Boeotian cities which resisted. They continued on until reaching the abandoned city of Athens. The Greeks consolidated to the Peloponneses and destroyed most of the Persian navy in the Battle of Salamis. The remaining Persians retreated back to Asia after suffering a major defeat at the Battle of Plataea, which saw the destruction of much of the Persian army.