Having in vain summoned Amphipolis to surrender, Philip commenced a strenuous siege, assailing the walls with battering-rams and other military engines. The weak points of the fortification must have been well known to him, from his own soldiers who had been recently in garrison. The inhabitants defended themselves with vigor; but such was now the change of circumstances, that they were forced to solicit their ancient enemy Athens for aid against the Macedonian prince. Their envoys Hierax and Stratokles, reaching Athens shortly after the successful close of the Athenian expedition to Eubœa, presented themselves before the public assembly, urgently inviting the Athenians to come forthwith and occupy Amphipolis, as the only chance of rescue from Macedonian dominion.[486] We are not certain whether the Social War had yet broken out; if it had, Athens would be too much pressed with anxieties arising out of so formidable a revolt, to have means disposable even for the tempting recovery of the long-lost Amphipolis. But at any rate Philip had foreseen and counterworked the prayers of the Amphipolitans. He sent a courteous letter to the Athenians, acquainting them that he was besieging the town, yet recognizing it as belonging of right to them, and promising to restore it to them when he should have succeeded in the capture.[487] [486] Demosthenes, Olynth. i. p. 11. s. 8 ... εἰ γὰρ, ὅθ᾽ ἥκομεν Εὐβοεῦσι βεβοηθηκότες καὶ παρῆσαν Ἀμφιπολιτῶν Ἱέραξ καὶ Στρατοκλῆς ἐπὶ τουτὶ τὸ βῆμα, κελεύοντες ἡμᾶς πλεῖν καὶ παραλαμβάνειν τὴν πόλιν, τὴν αὐτὴν παρειχόμεθ᾽ ὑπὲρ ἡμῶν αὐτῶν προθυμίαν ἥνπερ ὑπὲρ τῆς Εὐβοέων σωτηρίας, εἴχετ᾽ ἂν Ἀμφίπολιν τότε καὶ πάντων τῶν μετὰ ταῦτα ἂν ἦτε ἀπαλλαγμένοι πραγμάτων. [487] Demosthenes cont. Aristokrat. p. 659. s. 138. ... κἀκεῖνο εἰδότες, ὅτι Φίλιππος, ὅτε μὲν Ἀμφίπολιν ἐπολιόρκει, ἵν᾽ ὑμῖν παραδῷ, πολιορκεῖν ἔφη· ἐπειδὴ δ᾽ ἔλαβε, καὶ Ποτείδαιαν προσαφείλετο. Also the Oration De Halonneso, p. 83. s. 28. ... τῆς δ᾽ ἐπιστολῆς, ἣν πρὸς ὑμᾶς ἔπεμψεν (Philip) ὅτ᾽ Ἀμφίπολιν ἐπολιόρκει, ἐπιλέλησται, ἐν ᾗ ὡμολόγει τὴν Ἀμφίπολιν ὑμετέραν εἶναι· ἔφη γὰρ ἐκπολιορκήσας ὑμῖν ἀποδώσειν ὡς οὖσαν ὑμετέραν, ἀλλ᾽ οὐ τῶν ἐχόντων.