The manoeuvre, so far as concerned its immediate purpose, was completely successful. Phormio, much against his will, was obliged to leave his station outside the strait, and go to the aid of Naupactus, which had been left undefended. Great was the delight of the Peloponnesian captains when they saw the little Athenian squadron creeping close, in single file, along the northern side of the gulf, for they thought that not one of the twenty would escape them. At a given signal, the whole fleet formed into line, resuming its original order, four deep, and bore down upon the Athenians. Eleven of Phormio's triremes succeeded in clearing the strait, and getting into the open waters in the direction of Naupactus; but the remaining nine were overtaken and driven aground, and their crews, except those who escaped by swimming, were put to the sword. Some of these vessels were towed off as prizes by the Peloponnesians, and one they captured with all her crew. The rest were saved by the valour of the Messenian soldiers, who had followed the movements of Phormio's vessels along the shore, and now did good service by boarding the stranded triremes, and hauling them to land, after a sharp tussle with the enemy. Meanwhile the eleven ships which had eluded the attack were hotly pursued by the twenty fast-sailing vessels on the Peloponnesian right wing. All but one got through in safety, and took refuge in the harbour of Naupactus, and drawing up in line, with their prows outwards, prepared to defend themselves if the enemy advanced further against them. But the rearmost vessel was hard pressed by a Leucadian ship, and the rest of the pursuers followed at a considerable distance, singing the paean [Footnote: A song of victory.] as they rowed, and expecting an easy victory. Now, however, occurred one of those sudden turns of fortune so frequent in the course of a sea-fight. The Athenian trireme which had been left far behind in the chase, made a sudden sweep round a merchant-vessel anchored at the mouth of the harbour, struck her pursuer amidships, and sank her.