The senate saw that it had delayed too long already, and that it was time to put an end to such proceedings. The expulsion of the Thracian chieftain Abrupolis who was in alliance with the Romans, and the alliances of Macedonia with the Byzantines, Aetolians, and part of the Boeotian cities, were equally violations of the peace of 557, and sufficed for the official war-manifesto: the real ground of war was that Macedonia was seeking to convert her formal sovereignty into a real one, and to supplant Rome in the protectorate of the Hellenes. As early as 581 the Roman envoys at the Achaean diet stated pretty plainly, that an alliance with Perseus was equivalent to casting off the alliance of Rome. In 582 king Eumenes came in person to Rome with a long list of grievances and laid open to the senate the whole situation of affairs; upon which the senate unexpectedly in a secret sitting resolved on an immediate declaration of war, and furnished the landing-places in Epirus with garrisons. For the sake of form an embassy was sent to Macedonia, but its message was of such a nature that Perseus, perceiving that he could not recede, replied that he was ready to conclude with Rome a new alliance on really equal terms, but that he looked upon the treaty of 557 as cancelled; and he bade the envoys leave the kingdom within three days. Thus war was practically declared.
This was in the autumn of 582. Perseus, had he wished, might have occupied all Greece and brought the Macedonian party everywhere to the helm, and he might perhaps have crushed the Roman division of 5000 men stationed under Gnaeus Sicinius at Apollonia and have disputed the landing of the Romans. But the king, who already began to tremble at the serious aspect of affairs, entered into discussions with his guest-friend the consular Quintus Marcius Philippus, as to the frivolousness of the Roman declaration of war, and allowed himself to be thereby induced to postpone the attack and once more to make an effort for peace with Rome: to which the senate, as might have been expected, only replied by the dismissal of all Macedonians from Italy and the embarkation of the legions. Senators of the older school no doubt censured the "new wisdom" of their colleague, and his un-Roman artifice; but the object was gained and the winter passed away without any movement on the part of Perseus. The Romati diplomatists made all the more zealous use of the interval to deprive Perseus of any support in Greece. They were sure of the Achaeans. Even the patriotic party among them - who had neither agreed with those social movements, nor had soared higher than the longing after a prudent neutrality - had no idea of throwing themselves into the arms of Perseus; and, besides, the opposition party there had now been brought by Roman influence to the helm, and attached itself absolutely to Rome. The Aetolian league had doubtless asked aid from Perseus in its internal troubles; but the new strategus, Lyciscus, chosen under the eyes of the Roman ambassadors, was more of a Roman partisan than the Romans themselves. Among the Thessalians also the Roman party retained the ascendency. Even the Boeotians, old partisans as they were of Macedonia, and sunk in the utmost financial disorder, had not in their collective capacity declared openly for Perseus; nevertheless at least three of their cities, Thisbae, Haliartus and Coronea, had of their own accord entered into engagements with him. When on the complaint of the Roman envoy the government of the Boeotian confederacy communicated to him the position of things, he declared that it would best appear which cities adhered to Rome, and which did not, if they would severally pronounce their decision in his presence; and thereupon the Boeotian confederacy fell at once to pieces. It is not true that the great structure of Epaminondas was destroyed by the Romans; it actually collapsed before they touched it, and thus indeed became the prelude to the dissolution of the other still more firmly consolidated leagues of Greek cities[3]. With the forces of the Boeotian towns friendly to Rome the Roman envoy Publius Lentulus laid siege to Haliartus, even before the Roman fleet appeared in the Aegean.
Chalcis was occupied with Achaean, and the province of Orestis with Epirot, forces: the fortresses of the Dassaretae and Illyrians on the west frontier of Macedonia were occupied by the troops of Gnaeus Sicinius; and as soon as the navigation was resumed, Larisa received a garrison of 2000 men. Perseus during all this remained inactive and had not a foot's breadth of land beyond his own territory, when in the spring, or according to the official calendar in June, of 583, the Roman legions landed on the west coast. It is doubtful whether Perseus would have found allies of any mark, even had he shown as much energy as he displayed remissness; but, as circumstances stood, he remained of course completely isolated, and those prolonged attempts at proselytism led, for the time at least, to no result. Carthage, Genthius of Illyria, Rhodes and the free cities of Asia Minor, and even Byzantium hitherto so very friendly with Perseus, offered to the Romans vessels of war; which these, however, declined. Eumenes put his land army and his ships on a war footing. Ariarathes king of Cappadocia sent hostages, unsolicited, to Rome. The brother-in-law of Perseus, Prusias II. king of Bithynia, remained neutral. No one stirred in all Greece. Antiochus IV. king of Syria, designated in court style "the god, the brilliant bringer of victory", to distinguish him from his father the "Great", bestirred himself, but only to wrest the Syrian coast during this war from the entirely impotent Egypt.
3. The legal dissolution of the Boeotian confederacy, however, took place not at this time, but only after the destruction of Corinth (Pausan. vii. 14, 4; xvi. 6).