Battle of Naupactus The Battle of Naupactus was a naval battle in the Peloponnesian War . The battle , which took place a week after the Athenian victory at Rhium , set an Athenian fleet of twenty ships , commanded by Phormio , against a Peloponnesian fleet of seventy - seven ships , commanded by Cnemus . In the battle , the Peloponnesians drew the Athenians out from their anchorage at Antirrhium by sailing into the Corinthian gulf , moving as if to attack the vital Athenian base at Naupactus . The Athenians were forced to shadow their movements , sailing eastward along the northern shore of the gulf . Attacking suddenly , the Peloponnesians drove nine Athenian ships ashore and pursued the others towards Naupactus ; victory seemed securely in their hands . At the entrance to the harbor of Naupactus , however , the last Athenian ship to reach the harbor turned the tide by circling around an anchored merchant ship to ram and sink its leading pursuer . Confusion set in among the Peloponnesians , and the newly emboldened Athenians set out after them and routed them . In all , the Athenians recaptured all but one of their nine grounded ships and seized six Peloponnesian ships to boot . This surprising victory preserved Athens ' naval dominance and kept Naupactus secure ; the arrival of an additional twenty Athenian ships shortly afterwards secured the victory and put an end to Sparta ' s attempt to take the offensive in the Northwest . Prelude . In 429 BC , the Spartan government had ordered the navarch Cnemus to launch an offensive in the Corinthian gulf and northwestern Greece aimed at knocking several Athenian allies out of the Peloponnesian War . Ideally , the Spartans hoped to capture the Athenian base at Naupactus , from which the Athenians had been harassing Corinthian shipping . That offensive , however , suffered a severe setback when Cnemus was turned back on land by the Acarnania ns at Stratus , while a Peloponnesian fleet of forty - seven ships was routed by Phormio ' s twenty ships at Rhium . The Spartan government , dismayed by this unexpected reversal , dispatched several advisors ( including the aggressive and talented Brasidas ) to oversee Cnemus as he resumed the offensive . Phormio , meanwhile , sent to Athens for reinforcements , and twenty ships were sent out to him ; these were ordered to first sail to Crete to attack Cydonia , and as a result did not arrive in time to participate in the battle . Cnemus and the advisors , combining the ships that Cnemus had taken with him to Stratus with those retreating from Rhium and raising more ships levied from Sparta ' s allies on the gulf , had soon assembled a fleet of seventy - seven ships . The admirals then advanced with this fleet to Panormus , in Achaea , where they met up with the Peloponnesian infantry . Phormio , meanwhile , brought his ships up to Antirrhium , across the strait of Rhium from the Peloponnesians . Here , he was in position to move against the enemy fleet if it attempted to sail west into the open sea ; if he allowed it to escape in this way , he would essentially have surrendered Athens ' dominance over the sea , and might well have found himself blockaded in Naupactus . Battle . With the fleets at anchor across the strait from each other , it fell to the Peloponnesians to initiate a battle , as they wished to force an action before the Athenian reinforcements arrived . After six or seven days at Rhium , therefore , the Spartan commanders led their fleet eastward into the Corinthian Gulf . The Athenians , who in the previous battle had been able to take advantage of their superior maneuverability in the open sea , were reluctant to enter the constricted waters of the Gulf , but were forced to follow the Peloponnesians in order to protect Naupactus , which had been left ungarrisoned . The twenty Athenian ships entered the gulf sailing in single file along the northern shore ; the Messenian hoplite s from Naupactus marched along the shore beside them . On the southern shore , the Peloponnesian fleet was sailing in four lines , parallel to the shore . On the right of these lines , leading the advance into the gulf , were the twenty best and fastest ships in the fleet , which had been assigned the job of preventing the Athenians from escaping when the Peloponnesians attacked . Seeing the Athenians in the gulf and sailing in single file , Cnemus gave the signal for his ships to attack . The Peloponnesian fleet turned at once and raced across the gulf at the Athenians . The Athenians attempted to flee , but only the eleven leading ships were able to slip around the Peloponnesian right wing and flee towards Naupactus ; the remaining nine were cornered , driven ashore , and captured , while the twenty elite Peloponnesian ships from the right wing set out after the fleeing Athenian eleven . Ten Athenian ships reached Naupactus safely and took up positions at the mouth of the harbor , prows facing outwards , ready to defend against any attempt to enter the harbor . The last Athenian ship was fleeing towards the harbor , with the Peloponnesians ( who were already chanting the victory paean ) pursuing it closely , when it came alongside a merchant ship anchored outside the harbor . Using the merchant ship to protect its flanks while he turned , the Athenian captain spun his ship 270 degrees and rammed his leading pursuer in the side , sinking it . Although the Peloponnesians still held a great numerical advantage , the shock of this single action , which disheartened the Peloponnesian crews and reenvigorated the Athenians , proved sufficient to turn the tide of the battle . Confusion set in among the Peloponnesians ; some rowers in leading ships dropped their oars to allow the main body to catch up with them — thus leaving themselves immobile and vulnerable in the face of an enemy force ; other ships ran aground as a result of their captains ' ignorance of the coastline . The ten Athenian ships in the harbor rushed out and joined the attack , and the Peloponnesians were instantly routed . The Athenians captured six ships in the pursuit , and recovered all but one of their own ships which had been taken earlier . Although both sides claimed victory and set up trophies , it was clear who had won the battle ; the Peloponnesians , fearing the arrival of the Athenian reinforcements , retreated to Corinth under cover of darkness several days after the battle , and the Athenians continued to hold Naupactus and dominate the gulf . Aftermath . The Athenian victory at Naupactus put an end to Sparta ' s attempt to challenge Athens in the Corinthian gulf and the Northwest , and secured Athens ' dominance at sea . At Naupactus , the Athenians ' backs had been against the wall ; a defeat there would have lost Athens its foothold in the Corinthian gulf and encouraged the Peloponnesians to attempt further aggressive operations at sea . In 428 BC , the Spartans would be so cowed by the memory of their defeats at Phormio ' s hands that they sent no aid to Athens ' rebellious subject Mytilene in that year . In 427 , when they finally did send a fleet , the commander was so afraid of being caught at sea by the Athenians that he fled home without accomplishing anything .