It was evident, even in time of peace, what course Demosthenes would steer in the commonwealth; for whatever was done by the Macedonian, he criticized and found fault with, and upon all occasions was stirring up the people of Athens, and inflaming them against him. Therefore, in the court of Philip, no man was so much talked of, or of so great account as he; and when he came thither, one of the ten ambassadors who were sent into Macedonia, though all had audience given them, yet his speech was answered with most care and exactness. But in other respects, Philip entertained him not so honourably as the rest, neither did he show him the same kindness and civility with which he applied himself to the party of Aeschines and Philocrates. So that, when the others commended Philip for his able speaking, his beautiful person, nay, and also for his good companionship in drinking, Demosthenes could not refrain from cavilling at these praises; the first, he said, was a quality which might well enough become a rhetorician, the second a woman, and the last was only the property of a sponge; no one of them was the proper commendation of a prince.
But when things came at last to war, Philip on the one side being not able to live in peace, and the Athenians, on the other side, being stirred up by Demosthenes, the first action he put them upon was the reducing of Euboea, which, by the treachery of the tyrants, was brought under subjection to Philip. And on his proposition, the decree was voted, and they crossed over thither and chased the Macedonians out of the island. The next was the relief of the Byzantines and Perinthians, whom the Macedonians at that time were attacking. He persuaded the people to lay aside their enmity against these cities, to forget the offences committed by them in the Confederate War, and to send them such succours as eventually saved and secured them. Not long after, he undertook an embassy through the states of Greece, which he solicited and so far incensed against Philip that, a few only excepted, he brought them all into a general league. So that, besides the forces composed of the citizens themselves, there was an army consisting of fifteen thousand foot and two thousand horse, and the money to pay these strangers was levied and brought in with great cheerfulness. On which occasion it was, says Theophrastus, on the allies requesting that their contributions for the war might be ascertained and stated, Crobylus, the orator, made use of the saying, "War can't be fed at so much a day." Now was all Greece up in arms, and in great expectation what would be the event. The Euboeans, the Achaeans, the Corinthians, the Megarians, the Leucadians, and Corcyraeans, their people and their cities, were all joined together in a league. But the hardest task was yet behind, left for Demosthenes, to draw the Thebans into this confederacy with the rest. Their country bordered next upon Attica, they had great forces for the war, and at that time they were accounted the best soldiers of all Greece, but it was no easy matter to make them break with Philip, who, by many good offices, had so lately obliged them in the Phocian war; especially considering how the subjects of dispute and variance between the two cities were continually renewed and exasperated by petty quarrels, arising out of the proximity of their frontiers.
But after Philip, being now grown high and puffed up with his good success at Amphissa, on a sudden surprised Elatea and possessed himself of Phocis, and the Athenians were in a great consternation, none durst venture to rise up to speak, no one knew what to say, all were at a loss, and the whole assembly in silence and perplexity, in this extremity of affairs Demosthenes was the only man who appeared, his counsel to them being alliance with the Thebans. And having in other ways encouraged the people, and, as his manner was, raised their spirits up with hopes, he, with some others, was sent ambassador to Thebes. To oppose him, as Marsyas says, Philip also sent thither his envoys, Amyntas and Clearchus, two Macedonians, besides Daochus, a Thessalian, and Thrasydaeus. Now the Thebans, in their consultations, were well enough aware what suited best with their own interest, but every one had before his eyes the terrors of war, and their losses in the Phocian troubles were still recent: but such was the force and power of the orator, fanning up, as Theopompus says, their courage, and firing their emulation, that, casting away every thought of prudence, fear, or obligation, in a sort of divine possession, they chose the path of honour, to which his words invited them. And this success, thus accomplished by an orator, was thought to be so glorious and of such consequence, that Philip immediately sent heralds to treat and petition for a peace: all Greece was aroused, and up in arms to help. And the commanders-in-chief, not only of Attica, but of Boeotia, applied themselves to Demosthenes, and observed his directions. He managed all the assemblies of the Thebans, no less than those of the Athenians; he was beloved both by the one and by the other, and exercised the same supreme authority with both; and that not by unfair means, or without just cause, as Theopompus professes, but indeed it was no more than was due to his merit.