Lesson 5: Warfare in Ancient Greece

The Persian Wars began when Athens helped Ionian Greeks rebel against Persia. As a result, the furious Persian King Darius, and later his son Xerxes, invaded Greece. Despite being outnumbered, the Greek city-states, including rivals Athens and Sparta, temporarily united. This cooperation was crucial because it allowed them to combine their strengths—like Athenian naval power and Spartan military discipline—to successfully defend their homeland against a much larger and more powerful invading empire.

The Greeks won key battles using superior strategy, not just brute force.

• At Marathon, the Athenians surprised the Persians with a sudden phalanx charge.
• At Salamis, the Athenian general Themistocles lured the large Persian fleet into a narrow strait, where their numbers became a disadvantage.

These victories show that understanding geography and using clever tactics can overcome a stronger opponent. This connects to how their unity led to victory.

After the Persian Wars, Athens created the Delian League to protect against future invasions. However, Athens began to dominate the alliance. They forced members to stay, moved the league's treasury to Athens, and used the money to rebuild their own city, including the Parthenon. This shift from a protective ally to an imperial ruler caused deep resentment among other Greek city-states, especially Sparta, and planted the seeds for future conflict.

Greek unity dissolved as two powerful, opposing alliances emerged: the Delian League, led by democratic Athens, and the Peloponnesian League, led by oligarchic Sparta. Because each feared the other's growing power and influence, tensions escalated. The final trigger was an Athenian trade ban on a Spartan ally. This conflict, known as the Peloponnesian War, was inevitable as both sides believed they were destined to rule Greece, leading to a devastating civil war.

The 27-year war between Athens and Sparta had catastrophic effects. While Sparta's army was strong, it couldn't breach Athens' walls, which received supplies by sea. Then, a plague weakened Athens, and a disastrous invasion of Sicily crippled its navy. Ultimately, with financial help from their old enemy, Persia, Sparta built a navy and defeated Athens. The war exhausted all the city-states, ending Athens' golden age and leaving Greece vulnerable to outside conquest.