Meanwhile, however, the occasion for declaring war, which Rome desired, had been furnished from another quarter. The Athenians in their silly and cruel vanity had put to death two unfortunate Acarnanians, because these had accidentally strayed into their mysteries. When the Acarnanians, who were naturally indignant, asked Philip to procure them satisfaction, he could not refuse the just request of his most faithful allies, and he allowed them to levy men in Macedonia and, with these and their own troops, to invade Attica without a formal declaration of war. This, it is true, was no war in the proper sense of the term; and, besides, the leader of the Macedonian band, Nicanor, immediately gave orders to his troops to retreat, when the Roman envoys, who were at Athens at the time, used threatening language (in the end of 553). But it was too late. An Athenian embassy was sent to Rome to report the attack made by Philip on an ancient ally of the Romans; and, from the way in which the senate received it, Philip saw clearly what awaited him; so that he at once, in the very spring of 554, directed Philocles, his general in Greece, to lay waste the Attic territory and to reduce the city to extremities.

The senate now had what they wanted; and in the summer of 554 they were able to propose to the comitia a declaration of war "on account of an attack on a state in alliance with Rome". It was rejected on the first occasion almost unanimously: foolish or evil-disposed tribunes of the people complained of the senate, which would allow the citizens no rest; but the war was necessary and, in strictness, was already begun, so that the senate could not possibly recede. The burgesses were induced to yield by representations and concessions. It is remarkable that these concessions were made mainly at the expense of the allies. The garrisons of Gaul, Lower Italy, Sicily, and Sardinia, amounting in all to 20,000 men, were exclusively taken from the allied contingents that were in active service - quite contrary to the former principles of the Romans. All the burgess troops, on the other hand, that had continued under arms from the Hannibalic war, were discharged; volunteers alone, it was alleged, were to be enrolled for the Macedonian war, but they were, as was afterwards found, for the most part forced volunteers - a fact which in the autumn of 555 called forth a dangerous military revolt in the camp of Apollonia. Six legions were formed of the men newly called out; of these two remained in Rome and two in Etruria, and only two embarked at Brundisium for Macedonia, led by the consul Publius Sulpicius Galba. Thus it was once more clearly demonstrated, that the sovereign burgess assemblies, with their shortsighted resolutions dependent often on mere accident, were no longer at all fitted to deal with the complicated and difficult relations into which Rome was drawn by her victories; and that their mischievous intervention in the working of the state machine led to dangerous modifications of the measures which in a military point of were necessary, and to the still more dangerous course of treating the Latin allies as inferiors.

The position of Philip was very disadvantageous. The eastern states, which ought to have acted in unison against all interference of Rome and probably under other circumstances would have so acted, had been mainly by Philip's fault so incensed at each other, that they were not inclined to hinder, or were inclined even to promote, the Roman invasion. Asia, the natural and most important ally of Philip, had been neglected by him, and was moreover prevented at first from active interference by being entangled in the quarrel with Egypt and the Syrian war. Egypt had an urgent interest in keeping the Roman fleet out of the eastern waters; even now an Egyptian embassy intimated at Rome very plainly, that the court of Alexandria was ready to relieve the Romans from the trouble of intervention in Attica. But the treaty for the partition of Egypt concluded between Asia and Macedonia threw that important state thoroughly into the arms of Rome, and compelled the cabinet of Alexandria to declare that it would only intermeddle in the affairs of European Greece with consent of the Romans. The Greek commercial cities, with Rhodes, Pergamus, and Byzantium at their head, were in a position similar, but of still greater perplexity. They would under other circumstances have beyond doubt done what they could to close the eastern seas against the Romans; but the cruel and destructive policy of conquest pursued by Philip had driven them to an unequal struggle, in which for their self-preservation they were obliged to use every effort to implicate the great Italian power. In Greece proper also the Roman envoys, who were commissioned to organize a second league against Philip there, found the way already substantially paved for them by the enemy. Of the anti-Macedonian party - the Spartans, Eleans, Athenians, and Aetolians - Philip might perhaps have gained the latter, for the peace of 548 had made a deep, and far from healed, breach in their friendly Alliance with Rome; but apart from the old differences which subsisted between Aetolia and Macedonia regarding the Thessalian towns withdrawn by Macedonia from the Aetolian confederacy - Echinus, Larissa Cremaste, Pharsalus, and Thebes in Phthiotis - the expulsion of the Aetolian garrisons from Lysimachia and Cius had produced fresh exasperation against Philip in the minds of the Aetolians. If they delayed to join the league against him, the chief reason doubtless was the ill-feeling that continued to prevail between them and the Romans.

It was a circumstance still more ominous, that even among the Greek states firmly attached to the interests of Macedonia - the Epirots, Acarnanians, Boeotians, and Achaeans - the Acarnanians and Boeotians alone stood steadfastly by Philip. With the Epirots the Roman envoys negotiated not without success; Amynander, king of the Athamanes, in particular closely attached himself to Rome. Even among the Achaeans, Philip had offended many by the murder of Aratus; while on the other hand he had thereby paved the way for a more free development of the confederacy. Under the leadership of Philopoemen (502-571, for the first time strategus in 546) it had reorganized its military system, recovered confidence in itself by successful conflicts with Sparta, and no longer blindly followed, as in the time of Aratus, the policy of Macedonia. The Achaean league, which had to expect neither profit nor immediate injury from the thirst of Philip for aggrandizement, alone in all Hellas looked at this war from an impartial and national-Hellenic point of view. It perceived - what there was no difficulty in perceiving - that the Hellenic nation was thereby surrendering itself to the Romans even before these wished or desired its surrender, and attempted accordingly to mediate between Philip and the Rhodians; but it was too late. The national patriotism, which had formerly terminated the federal war and had mainly contributed to bring about the first war between Macedonia and Rome, was extinguished the Achaean mediation remained fruitless, and in vain Philip visited the cities and islands to rekindle the zeal of the nation - its apathy was the Nemesis for Cius and Abydus. The Achaeans, as they could effect no change and were not disposed to render help to either party, remained neutral.

In the autumn of 554 the consul, Publius Sulpicius Galba, landed with his two legions and 1000 Numidian cavalry accompanied even by elephants derived from the spoils of Carthage, at Apollonia; on receiving accounts of which the king returned in haste from the Hellespont to Thessaly. But, owing partly to the far-advanced season, partly to the sickness of the Roman general, nothing was undertaken by land that year except a reconnaissance in force, in the course of which the townships in the vicinity, and in particular the Macedonian colony Antipatria, were occupied by the Romans. For the next year a joint attack on Macedonia was concerted with the northern barbarians, especially with Pleuratus, the then ruler of Scodra, and Bato, prince of the Dardani, who of course were eager to profit by the favourable opportunity.