By 425 B.C., the Spartans and the Athenians were locked in a deadly struggle without prospects of either
victory or negotiation. The Spartans had little to show for their efforts except the capture of Plataea in 427
B.C. The Athenians, too, were exhausted. Yet in 425 B.C., the Athenian general Demosthenes garrisoned a
fort near Pylos, on the shores of Messenia, and frightened the Spartans into a fateful blunder. The Spartans,
fearing a helot rebellion, besieged the fort, located on the northern peninsula enclosing the Bay of
Navarino. The Athenian fleet unexpectedly returned to raise the siege and captured the Spartan triremes on
the beaches. The Athenian fleet also cut off a Spartan regiment stationed on the island of Sphacteria, which
protected the bay. In the summer of 425 B.C., Sparta offered peace terms for the first time. Nicias, the
cautious Athenian senior general who styled himself Pericles’s heir, urged peace, but the assembly rejected
the terms. Cleon and Demosthenes launched a surprise attack and captured 292 of the Spartans and
perioikoi on Sphacteria. With the prisoners in Athenian hands, the Spartans dared not invade Attica while
the Athenians had means to raise tribute and strike a blow against the Spartan alliance.