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The Great Civil War of Greece
The Peloponnesian War was a long and destructive conflict that lasted nearly thirty years and involved the two most powerful Greek states: Athens, with its vast naval empire, and Sparta, supported by its land-based alliance system. It is considered the most devastating war in Greek history. The fighting brought not only military destruction but also deep moral and cultural decline, described vividly by the historian Thucydides. The war marks the end of Athens’ Golden Age and the beginning of a long period of instability for the Greek world.
Causes of the War
The origins of the conflict lay not in a single event but in deep structural tensions. The rise of Athens after the Persian Wars created a new imbalance. Athens had built a powerful naval empire based on the Delian League, while Sparta continued to dominate the Peloponnesian League. These two systems represented opposing political ideals: Athens embodied democratic expansion, while Sparta upheld a conservative oligarchic order.
Sparta feared Athens’ growing power, a fear that Thucydides identifies as the main cause of the war. Many Greek poleis found themselves caught between the two blocs, pressured into choosing sides. A series of direct conflicts, particularly those involving Corinth and its colonies, increased tensions. The Athenian Megarian Decree, which imposed severe economic sanctions, contributed further to the escalation. Alliance obligations ultimately drew Sparta into the conflict. In 431 BCE, open war finally broke out.
The Archidamian War (431–421 BCE)
The first phase of the Peloponnesian War is named after the Spartan king Archidamus II. The strategies of the two sides reflected their different strengths. Each year, the Spartan army invaded Attica and devastated the countryside, forcing the rural population to take refuge behind the Long Walls that connected Athens with its port at Piraeus. Athens relied on its powerful fleet to conduct raids along the Peloponnesian coast and maintain control of the sea.
In 430 BCE, a devastating plague broke out in the overcrowded city. It killed roughly a third of the population, including the statesman Pericles, and severely weakened Athenian morale. Eventually, after years of indecisive fighting, the Peace of Nicias was concluded in 421 BCE. This truce, however, remained fragile, as many allies on both sides refused to accept its terms.
The Sicilian Expedition (415–413 BCE)
The Sicilian Expedition was the most ambitious and disastrous military undertaking in Athenian history. Athens sought to conquer Syracuse and extend its influence in the western Mediterranean. A massive fleet and army were sent to Sicily, first under the command of Alcibiades and later under Nicias. Internal divisions, poor planning, and unfamiliarity with local conditions undermined the campaign. When Sparta and other Greek states came to the aid of Syracuse, the Athenian forces were gradually trapped.
The expedition ended in total catastrophe. The entire Athenian fleet was destroyed, and the army was either killed or taken prisoner. The defeat caused enormous economic, military, and psychological damage. Thucydides described it as the greatest disaster the Greeks had experienced up to that time.
The Decelean War (413–404 BCE)
After the Sicilian disaster, Sparta adopted a far more aggressive strategy. It fortified the town of Decelea in Attica, permanently occupying Athenian territory and cutting off key supply routes. The Spartans, supported financially by Persia, built a new fleet under the command of Lysander. They encouraged revolts among Athens’ allies and attacked the silver mines at Laurion, a vital source of revenue.
Athens struggled with internal unrest, which culminated in an oligarchic coup in 411 BCE. A short-lived regime known as the Council of the Four Hundred gained power, but democracy was soon restored. Despite severe losses, the Athenians continued to fight, hoping to preserve their empire. Their efforts came to an end in 405 BCE, when Lysander annihilated the Athenian fleet at the Battle of Aegospotami. Without ships, Athens could no longer resist.
In 404 BCE, Athens surrendered. Its Long Walls were torn down, the fleet was handed over, and the empire collapsed. Sparta installed an oligarchic regime known as the Thirty Tyrants, although democracy returned shortly afterward.
Consequences of the War
The Peloponnesian War ended Athens’ position as a great power. The city remained culturally influential, but it no longer dominated Greek politics. Sparta briefly became the leading state in Greece, yet it was unable to manage its new responsibilities and soon faced conflicts with Persia, internal weaknesses, and challenges from Thebes.
The war left Greece economically exhausted. Farms and cities lay damaged, populations were reduced, and morale had collapsed after years of civil strife and betrayals. Although Athens eventually regained cultural vitality, it never recovered its former strength. The continuing rivalries among the poleis weakened the entire Greek world, creating the conditions for the emergence of Macedon in the fourth century BCE.
Significance of the Peloponnesian War
The Peloponnesian War is often described as the first example of a large-scale “systemic war,” pitting a land-based power against a naval empire. It reveals the destructive potential of civil conflict and long-term rivalry. Thucydides’ analysis of the war continues to shape political theory and the study of history today. The war marked the end of the Classical era and permanently altered the political landscape of Greece. The unity once achieved during the Persian Wars was lost, and the Greek poleis entered a period of fragmentation and decline.