In the fifth century BCE, ancient Greece comprised several major city-states. Each city-state was a nation unto itself, though they also shared the Greek language, a sense of cultural identity, and a public religion, as evidenced in shared gods and the Olympic Games. With the exception of Sparta’s military, the city-states’ armies were mostly made up of citizen-soldiers who were not professional warriors, but farmers and craftspeople who could not be away for campaigns without great personal loss of money and property. By the time of the Peloponnesian War, when Pericles gave his speech, the two most powerful city-states were Athens, which had a powerful navy, and Sparta, which had a strong infantry.

Sparta founded the Peloponnesian League around 550 BCE, based around the Peloponnese, a peninsula that forms the southern half of mainland Greece. The alliance included Sparta and Corinth, the two biggest city-states of the Peloponnese. In 490 BCE, the mighty Persian Empire attempted but failed to conquer all the Greeks. They renewed their attempt in 480 BCE and were decisively defeated the following year. During this second invasion, Athens was occupied and burned to the ground by the Persians.

In response to the Persian War, Athens founded the Delian League.