Thebes and Athens became military rivals during the late Archaic and early Classical eras because the Athenians supported the rights of the Plataeans (a smaller city-state located several miles south of Thebes) to live independent and free of Theban dominance. This rivalry was important because it led to the Thebans supporting the Persian Empire when it attempted to invade Athens.

Gelon was the ruler of Syracuse at the time of the Greco-Persian Wars. He, like many other rulers at the time, was a tyrant with near-absolute power. During the invasion of mainland Greece, by the Persian King Xerxes, in 480 BCE, he was asked to assist the Greek resistance. At the time Syracuse was one of the wealthiest and most powerful Greek city-states and their assistance would have been very useful. Gelon, however, demanded full control over all Greek forces and when the Athenians and Spartans refused he withdrew all offers of support and left the rest of Greece to defend itself.

Mardonius was one of the most high ranking members of the Persian army under King Xerxes. After Xerxes retired from Greece in 480 BCE (to return to the capital and preserve his authority), Mardonius took over command of the Persian forces in Greece. He led the Persian army at the Battle of Plataea where he was defeated and killed on the battlefield.

The Battle of Plataea was fought in 479 BCE in the plains to the north of Athens. It was the decisive land battle of the Greco-Persian Wars. It ended in victory for the Greek forces and the death of the Persian commander. The Persian army was forced to retreat and Greece had somehow defended itself against the mightiest empire in the world.

Tyrtaeus was a Spartan poet who probably lived in the late seventh century BCE. His poems focused on emphasizing Spartan martial prowess and on encouraging young Spartans to fight with strength and honor against the Messenians in the Second Messenian War. Tyrtaeus is an example of Spartan artistic endeavor — which was generally focused on promoting Spartan social values and obedience to the law.

Hostility between Sparta and Athens first began in the late sixth century, when Sparta sent an army to intervene on behalf of the Athenian aristocracy, who feared the loss of their power. The Spartan soldiers were turned back by the Athenian people, who fought to defend their city and the democratic reforms enacted by Cleisthenes. This created a natural and long lasting animosity between the two city-states. Their rivalry would dominate the next few hundred years of Greek history.

The land battle of Plataea and the naval battle of Mycale took place at approximately the same time in 479 BCE. They both ended in decisive victories for the ancient Greeks and brought to an end the attempted Persian conquest of the Greek mainland.

The Ionian Revolt took place from 499 to 494 BCE. The Ionians were Greeks who lived in Anatolia and had recently been conquered by the mighty Persian Empire. They revolted against Persian tyranny and sent emissaries to Athens asking for help. Athens came to the aid of the Ionians, but the revolt was crushed anyway. Apparently, King Darius of Persia was so incensed by the Athenians betrayal (as he saw it) that he resolved to destroy the city-state.

The Battle of Himera was part of the Carthaginian invasion of Sicily in 480 BCE. At the time, Sicily was part of the Greek-speaking world and the powerful city-state of Syracuse was located there. The Carthaginians invaded Sicily at the same time as the Persians were invading mainland Greece. The Battle of Himera ended in victory for Syracuse and the defeat of the Carthaginian expeditionary force.

The Sea-Peoples were a loosely organized, disparate group of bandits and migrants. They emerged out of some unknown catastrophe in Mycenaean Greece. The Sea-Peoples repeatedly invaded the Hittite Empire and the New Kingdom of Egypt in the twelfth and eleventh centuries and contributed to the decline of both.