Thucydides on the causes of the Peloponnesian War
The Peloponnesian War1, like most wars, had a complex origin. Thucydides reveals that the immediate
causes centered on disputes between Athens and Sparta on whether they had a free hand
in dealing with each other's allies. Violent disputes broke out both concerning
Athenian economic sanctions against the city-state of
Megara2, an ally of Sparta, and the
Athenian blockade of
Potidaea3, a city-state formerly allied to Athens but now in revolt and seeking help
from
Corinth4,
a principal ally of Sparta. The
deeper causes5 involved the antagonists' ambitions for hegemony, fears of each other's power,
and concern for freedom from interference by a strong rival.
Immediate causes of the war
The outbreak of the war came when the Spartans issued ultimatums to Athens that the
men of the Athenian assembly rejected at the urging of Pericles. The
Spartan
ultimatums promised attack unless Athens lifted its economic sanctions against the
city-state of Megara,
6 a Spartan ally that lay just
west of Athenian territory, and stopped its
military blockage of Potidaea,
7 a
strategically located city-state in northern Greece. The Athenians had forbidden the
Megarians from trading in all the harbors of the Athenian empire, a severe blow for
Megara, which derived much income from trade. The Athenians had imposed the
sanctions in retaliation for alleged Megarian encroachment on sacred land along the
border between the territory of Megara and Athens. As for Potidaea, it been an ally
of Athens but was now in rebellion. Potidaea retained ties to
Corinth8, the city that had originally founded it, and Corinth, an
ally of Sparta, had protested the Athenian blockade of its erstwhile colony. The
Corinthians were already angry at the Athenians for having supported the city-state
of
Corcyra9 in its earlier quarrel with
Corinth and securing an alliance with Corcyra and its formidable navy. The Spartans
issued the ultimatums in order to placate the Megarians and, more importantly, the
Corinthians with their powerful naval force.
Corinth had threatened to
withdraw from the Peloponnesian League10 and join a different international alliance if the Spartans delayed any
longer in backing them in their dispute with the Athenians over Potidaea. In this
way, the actions of lesser powers nudged the two great powers, Athens and Sparta,
over the brink to war in 431 B.C.
Deeper causes of the war
The disputes over Athenian action against Megara and Potidaea reflected the larger
issues of power motivating the hostility between Athens and Sparta. The Spartan
leaders feared that the Athenians would use their superiority in long-distance
offensive weaponry—the naval forces of the Delian League—to
destroy Spartan control over the members of the Peloponnesian League. The majority
in the Athenian assembly, for their part, resented Spartan interference in their
freedom of action. For example,
Thucydides portrays Pericles as making the
following arguments in a speech11 to convince his fellow
male citizens to reject the Spartan demands even if that means war: “If we
do go to war, harbor no thought that you went to war over a trivial affair. For you
this trifling matter is the assurance and the proof of your determination. If you
yield to their demands, they will immediately confront you with some larger demand,
since they will think that you only gave way on the first point out of fear. But if
you stand firm, you will show them that they have to deal with you as equals ...
When our equals, without agreeing to arbitration of the matter under dispute, make
claims on us as neighbors and state those claims as commands, it would be no better
than slavery to give in to them, no matter how large or how small the claim may
be.”
