The Romans and Asiatics met once more in the plain of the Cephissus, near Orchomenus. The numerous and excellent cavalry of the latter flung itself impetuously on the Roman infantry, which began to waver and give way: the danger was so urgent, that Sulla seized a standard and advancing with his adjutants and orderlies against the enemy called out with a loud voice to the soldiers that, if they should be asked at home where they had abandoned their general, they might reply - at Orchomenus. This had its effect; the legions rallied and vanquished the enemy's horse, after which the infantry were overthrown with little difficulty. On the following day the camp of the Asiatics was surrounded and stormed; far the greatest portion of them fell or perished in the Copaic marshes; a few only, Archelaus among the rest, reached Euboea. The Boeotian communities had severely to pay for their renewed revolt from Rome, some of them even to annihilation. Nothing opposed the advance into Macedonia and Thrace; Philippi was occupied, Abdera was voluntarily evacuated by the Pontic garrison, the European continent in general was cleared of the enemy. At the end of the third year of the war (669) Sulla was able to take up winter-quarters in Thessaly, with a view to begin the Asiatic campaign in the spring of 670[15], for which purpose he gave orders to build ships in the Thessalian ports.

Meanwhile the circumstances of Asia Minor also had undergone a material change. If king Mithradates had once come forward as the liberator of the Hellenes, if he had introduced his rule with the recognition of civic independence and with remission of taxes, they had after this brief ecstasy been but too rapidly and too bitterly undeceived. He had very soon emerged in his true character, and had begun to exercise a despotism far surpassing the tyranny of the Roman governors - a despotism which drove even the patient inhabitants of Asia Minor to open revolt. The sultan again resorted to the most violent expedients. His decrees granted independence to the townships which turned to him, citizenship to the metoeci, full remission of debts to the debtors, lands to those that had none, freedom to the slaves; nearly 15,000 such manumitted slaves fought in the army of Archelaus. The most fearful scenes were the result of this high-handed subversion of all existing order. The most considerable mercantile cities, Smyrna, Colophon, Ephesus, Tralles, Sardes, closed their gates against the king's governors or put them to death, and declared for Rome[16]. On the other hand the king's lieutenant Diodorus, a philosopher of note like Aristion, of another school, but equally available for the worst subservience, under the instructions of his master caused the whole town-council of Adramyttium to be put to death. The Chians, who were suspected of an inclination to Rome, were fined in the first instance in 2000 talents (480,000 pounds) and, when the payment was found not correct, they were en masse put on board ship and deported in chains under the charge of their own slaves to the coast of Colchis, while their island was occupied with Pontic colonists. The king gave orders that the chiefs of the Celts in Asia Minor should all be put to death along with their wives and children in one day, and that Galatia should be converted into a Pontic satrapy. Most of these bloody edicts were carried into effect either at Mithradates' own headquarters or in Galatia, but the few who escaped placed themselves at the head of their powerful tribes and expelled Eumachus, the governor of the king, out of their bounds. It may readily be conceived that such a king would be pursued by the daggers of assassins; sixteen hundred men were condemned to death by the royal courts of inquisition as having been implicated in such conspiracies.

While the king was thus by his suicidal fury provoking his temporary subjects to rise in arms against him, he was at the same time hard pressed by the Romans in Asia, both by sea and by land. Lucullus, after the failure of his attempt to lead forth the Egyptian fleet against Mithradates, had with better success repeated his efforts to procure vessels of war in the Syrian maritime towns, and reinforced his nascent fleet in the ports of Cyprus, Pamphylia, and Rhodes till he found himself strong enough to proceed to the attack. He dexterously avoided measuring himself against superior forces and yet obtained no inconsiderable advantages. The Cnidian island and peninsula were occupied by him, Samos was assailed, Colophon and Chios were wrested from the enemy.

Meanwhile Flaccus had proceeded with his army through Macedonia and Thrace to Byzantium, and thence, passing the straits, had reached Chalcedon (end of 668). There a military insurrection broke out against the general, ostensibly because he embezzled the spoil from the soldiers. The soul of it was one of the chief officers of the army, a man whose name had become a proverb in Rome for a true mob-orator, Gaius Flavius Fimbria, who, after having differed with his commander-in-chief, transferred the demagogic practices which he had begun in the Forum to the camp. Flaccus was deposed by the army and soon afterwards put to death at Nicomedia, not far from Chalcedon; Fimbria was installed by decree of the soldiers in his stead. As a matter of course he allowed his troops every indulgence; in the friendly Cyzicus, for instance, the citizens were ordered to surrender all their property to the soldiers on pain of death, and by way of warning example two of the most respectable citizens were at once executed. Nevertheless in a military point of view the change of commander-in-chief was a gain; Fimbria was not, like Flaccus, an incapable general, but energetic and talented.

At Miletopolis (on the Rhyndacus to the west of Brussa) he defeated the younger Mithradates, who as governor of the satrapy of Pontus had marched against him, completely in a nocturnal assault, and by this victory opened his way to Pergamus, the capital formerly of the Roman province and now of the Pontic king, whence he dislodged the king and compelled him to take flight to the port of Pitane not far off, with the view of there embarking. Just at that moment Lucullus appeared in those waters with his fleet; Fimbria adjured him to render assistance so that he might be enabled to capture the king. But the Optimate was stronger in Lucullus than the patriot; he sailed onward and the king escaped to Mitylene. The situation of Mithradates was even thus sufficiently embarrassed. At the end of 669 Europe was lost, Asia Minor was partly in rebellion against him, partly occupied by a Roman army; and he was himself threatened by the latter in his immediate vicinity. The Roman fleet under Lucullus had maintained its position on the Trojan coast by two successful naval engagements at the promontory of Lectum and at the island of Tenedos; it was joined there by the ships which had in the meanwhile been built by Sulla's orders in Thessaly, and by it position commanding the Hellespont it secured to the general of the Roman senatorial army a safe and easy passage next spring to Asia.

Mithradates attempted to negotiate. Under other circumstances no doubt the author of the edict for the Ephesian massacre could never have cherished the hope of being admitted at all to terms of peace with Rome; but amidst the internal convulsions of the Roman republic, when the ruling government had declared the general sent against Mithradates an outlaw and subjected his partisans at home to the most fearful persecutions, when one Roman general opposed the other and yet both stood opposed to the same foe, he hoped that he should be able to obtain not merely a peace, but a favourable peace. He had the choice of applying to Sulla or to Fimbria; he caused negotiations to be instituted with both, yet it seems from the first to have been his design to come to terms with Sulla, who, at least from the king's point of view, seemed decidedly superior to his rival. His general Archelaus, a instructed by his master, asked Sulla to cede Asia to the king and to expect in return the king's aid against the democratic party in Rome. But Sulla, cool and clear as ever, while urgently desiring a speedy settlement of Asiatic affairs on account of the position of things in Italy, estimated the advantages of the Cappadocian alliance for the war impending over him in Italy as very slight, and was altogether too much of a Roman to consent to so disgraceful and so injurious a concession.