However when, later in the year, Ambracia invades Acarnania, and the Acarnanians seek help from Demosthenes, who is patrolling the Ionian Sea coast with twenty Athenian ships, he reaches the Athenian naval base in the Gulf of Corinth at Naupactus and secures it just in time to defend it against a large Spartan army from Delphi under Eurylochus which has come to assist the Ambraciots.
In 426 BC, Spartan general Eurylochus, on his way to Naupactus, arrived to Delphi and sent a herald to Amfissa, in order to detach them from Athens and make the Amfissians leave him pass through their lands.