The Peloponnese appears in the Federalist essays as the territorial heart of the revived Achaean League and as the setting for a cautionary history of Greek political division. The league grew to embrace almost the whole peninsula, but jealousy among Greek powers, reliance on outside allies, and Roman manipulation eventually broke it apart; the example illustrates how internal dissension can destroy a union and expose its members to domination.

The Peninsula and the Achaean Revival

The Peloponnese enters the argument through the contrast between two Greek confederacies. While the Amphictyonic confederacy remained powerful, the Achaean association of less important cities made little figure in Greek affairs. After the former fell to Macedon, the Achaeans were initially spared, but the policy of Macedon’s successors changed: separate interests were encouraged among the cities, and the union dissolved. Some cities then endured Macedonian garrisons; others fell under rulers who emerged from their own disorder.

Oppression renewed the cities’ desire for liberty. A few reunited, others followed when opportunities arose to overthrow their tyrants, and the revived league soon extended across almost the whole Peloponnese. The peninsula is therefore not merely a geographic label: its breadth marks the reach of political cooperation restored from fragmentation. Yet that consolidation remained exposed to envy and rivalry elsewhere in Greece.

Rivalry, Intervention, and Ruin

As the Achaean League grew, Sparta and Athens became jealous of its rising influence, damping the prospect that all Greece might unite in a single confederacy. Fear of Macedon led the league to seek the alliance of the kings of Egypt and Syria, rivals of the Macedonian king. Cleomenes, king of Sparta, attacked the Achaeans without provocation and used his influence with those rulers to break their commitments to the league. The Achaeans faced a choice between submitting to Cleomenes and seeking aid from their former oppressor; they chose Macedon.

A Macedonian army defeated Cleomenes, but victory brought no secure independence. The Achaeans found that even their most abject compliance could obtain only permission to continue exercising their laws. Under Philip, further Greek combinations formed in response to tyranny. The Achaeans joined with the Aetolians and Athenians, but, finding themselves unequal to the struggle, again called in foreign arms, this time from Rome. Rome defeated Philip and subdued Macedon; then it fostered dissensions within the league, using Callicrates and other popular leaders to turn the Greeks against one another. By appealing to the members’ pride in their sovereignty, Rome drew them away from the union. The last hope of ancient liberty was thus divided, and Roman arms completed the ruin begun by Roman political influence: the Achaeans were cut to pieces, and Achaia was left under chains.

Political Lesson of the Historical Example

The Peloponnesian history supports the essays’ broader comparison between confederacies. A confederacy, the argument maintains, can help suppress faction and protect the internal tranquillity of its states while increasing their external force and security. But the Achaean experience shows how those purposes can be defeated when cities separate into competing interests, resent the influence of a rising member, or invite a powerful neighbor to settle their conflicts. A victorious ally may become a master, and a claim to protect local sovereignty can be used to dissolve the common political bond.

This example frames the danger as anarchy among members rather than tyranny at the head of a union. Set beside the essay’s account of a German confederacy whose laws addressed sovereigns rather than individuals, the Greek history reinforces the warning that formal federal powers do not themselves ensure cohesion. The Peloponnese’s story moves from dispersed cities, to a league approaching peninsula-wide unity, and finally to division and subjection. In the Federalist argument, that reversal makes the ancient landscape a measure of both the promise of union and the cost of allowing internal jealousy to undo it.