Mithradates came to the throne of Pontus in early youth. He cherished from the first ambitious schemes of extending his dominions. At first his efforts were directed against his neighbours on the north and east; when he attempted to extend his frontiers westward he naturally came into collision with the Romans. It is needless to go into details; it will suffice to say that war was declared in 89. The time suited Mithradates very well, for it found Rome in a very helpless condition. What is called the Social War, i.e., the revolt of the Italian allies against Rome, was still in progress, and there was positively no army available to meet the huge host, nearly 300,000 in all, which the King brought into the field. All that the Roman officers in Lesser Asia could do was to shut themselves up in such fortified towns as they could hope to hold against the King. Mithradates now gave orders for an act which was as foolish as it was wicked. He was at Ephesus—the fact shows how little remained to Rome—when he directed that all Italians sojourning in Lesser Asia should be put to death. Had he said "Romans," not "Italians," he might have secured the combination with himself of the Italian adversaries of Rome. As it was he hopelessly alienated them.

Nor did he make himself better liked by his new subjects in Asia. They found that in exchanging masters they had lost much more than they had gained. The Romans were often oppressive, but they had at least some kind of system, and were, in theory at least, subject to law; the King was a capricious tyrant, whose whims, often as cruel as they were strange, had to be instantaneously humoured under pain of death or torture. The end was that Mithradates was beaten everywhere. An army which he had sent into Greece was destroyed. His arms were equally unsuccessful in Asia. An attempt to make common cause with Sulla's political opponents—some of the democratic leaders were actually in arms—came to nothing. Finally, in 84 peace was made. The King had to give up all his conquests, to surrender for punishments the men who had taken a leading part in the massacre, and to pay a war indemnity of 20,000 talents.

After a somewhat uneasy peace of ten years war broke out again. Each side was suspicious of the other. Mithradates had steadily employed himself in increasing his dominions in every direction where he did not come into actual collision with Rome. Rome, on the other hand, had a way of receiving legacies of kingdoms, very much to the annoyance of those who conceived themselves to have a better title to the inheritance. In 75 , for instance, she took possession of Bithynia, which Mithradates had always coveted, in accordance with the will of Nicomedes III. The King naturally took offence at this proceeding, and as he saw at the same time a prospect of taking his great enemy at a disadvantage, he declared war. He hoped that Sertorius in Spain would make a diversion in his favour, and he also looked for help from the pirates who swarmed in the Mediterranean.

These expectations were but partially fulfilled. Sertorius was very near the end of his career, and could be practically ignored. Mithradates won a few successes here and there, but he had a very able soldier, Lucullus, to contend with. After a few months' fighting he had to fly from his kingdom and take refuge with his son-in-law, Tigranes, King of Armenia.

Lucullus now ventured on a very bold course of action. He sent envoys to Tigranes demanding the surrender of Mithradates. This was, of course, refused, as indeed Lucullus expected and even intended that it should be. The Roman general then crossed the Euphrates and marched on Tigranocerta. This was a new city, and was the creation, as it bore the name, of Tigranes. He had peopled it with inhabitants, taken, after the fashion of Eastern kings, from conquered or simply subject tribes, and had supplied it with all the conveniences and ornaments of Greek civilisation. Its walls, the historian tells us, were seventy feet high, and must have been of huge circuit, if there were parks and lakes within them. Lucullus laid siege to the city, though he could hardly have had sufficient force to invest it. It was not long before Tigranes moved to its relief. At first, indeed, he had simply refused to believe that the Romans could have made so audacious an advance, and with a savagery, in curious contrast with his veneer of civilisation, ordered the messenger who brought the unwelcome news to be crucified. When he learnt the truth, he raised a huge army—250,000 infantry and 50,000 cavalry are the numbers given us by historians—and marched to attack Lucullus.

Mithradates was with his son-in-law, and strongly advised him not to risk a battle. "Use your cavalry to cut off his supplies," was his advice, for the old King knew what Roman soldiers were when they were led by such a general as Lucullus. Tigranes laughed to scorn this prudent counsel. He could not conceive that the handful of men which were all that the Romans had to oppose to him, could possibly stand up against an army which was nearly twenty times as numerous. For Lucullus had divided his small force, leaving a part to carry on the siege of the city while he went to meet Tigranes with the remainder.

The battle that followed was one of the most remarkable in history, worthy to be ranked with Marathon, for, indeed, the odds were at least as great as any of which we have a record. Unfortunately for the fame of Lucullus there was no one to tell the story as it ought to have been told. The strategy of Lucullus was that employed times out of number with success by the leader of a regular army acting against an undisciplined host—he outflanked his opponents. What we can understand from the accounts, not easily reconcilable, is that a front attack was made, or rather threatened, by the Roman cavalry. It advanced, and then retreated, in seeming panic, and the Asiatics pursued in headlong haste. Mean while the outflanking movement had been made unseen by the infantry. Attacking the rear of the army they sent the camp-followers flying in wild confusion; these broke the lines of the infantry; the infantry in turn threw the horse-men into confusion. The panic once set up, the huge, unmanageable numbers of the Asiatic host did nothing but aggravate it. The pursuit was fierce and pitiless. Lucullus threatened the severest penalties against any soldier who should turn aside for a moment to encumber himself with spoil. For fifteen miles the road was strewed with costly chains and bracelets which no one picked up. The pursuit over, the men were allowed to appropriate all the treasures they could find. Five Romans, and five only, are said to have been slain. The enemy's dead were counted by tens of thousands.

This great victory had not, it is true, the permanent result which might have been expected. This failure was due to the weakness of the Government at home and the jealousy of parties. Lucullus was hampered by want of means, and had to share his authority with incompetent colleagues. It was not long before both Tigranes and Mithradates recovered all that they had lost.

But this was but a temporary falling back of the Roman power. The people, profoundly dissatisfied with the policy that had made such brilliant victories unproductive, put the supreme power into the hands of a man whom it could trust. In 67 Pompey cleared the Mediterranean of the pirates, and two years later he brought to an end the long struggle with Mithradates. Tigranes had made his submission to Rome, and, while surrendering all his conquests, had been permitted to retain his hereditary kingdom of Armenia. Mithradates was driven to take refuge in a remote region at the eastern end of the Black Sea. He had conceived, it is said, a bold scheme of raising the tribes to the north of that sea and falling upon Italy as the Gauls and as Hannibal had fallen upon it. But he had not the means of carrying out so large a project. His subjects, wearied of perpetual exactions, rebelled, led by one of his sons, and he saw that nothing remained but death. His wives and his daughters were compelled or possibly offered to drink poison. He drank it himself, but—so runs the story—had so fortified himself with antidotes, that the drug did not affect him. He then commanded a Celtic mercenary to render him the last service by a stroke of his sword. By his death the Roman dominion was practically established as far as the Euphrates. That it was not to be extended beyond it was practically proved by the events which I have now to relate.

Five years after the fall of Mithradates there was formed at Rome what is commonly called the First Triumvirate.

Of the three men who composed it Pompey had gained a great reputation as a soldier, Cæsar had acquired almost equal distinction by his victory in Gaul, while Crassus, though he had served with credit on more than one occasion, was distinctly inferior in this respect to his colleagues. He felt that such an inferiority would tell greatly against him when the spoils came to be divided. It was to the East that he looked for the opportunity that he desired. There had been trouble in the region beyond the Euphrates for some time, and Rome, accused of having failed to keep her treaty arrangement, was, of course, mixed up in it. In 55 , the year when Cæsar's command in Gaul had been renewed for a second period of five years, Crassus was elected Consul, his colleague being Pompey. The province allotted to him after his year of office was Syria, and he left Rome before the year was out to take up his command. He did not meet with anything like universal approval. The decree which gave him the province of Syria made no mention of Parthia, but everyone knew that Parthia was to be attacked, and there was a strong party that, either from prudence or from a sense of right, was strongly opposed to what was manifestly a war of aggression. One of the Tribunes of the People attempted to stop his departure from Rome, actually bidding his attendant detain him by force. This attempt failing, he took his stand at the gate by which Crassus was to depart, and on a hastily constructed altar performed some mysterious rite by which he devoted, under strange and awful curses, the head of Crassus to destruction. But Crassus persevered; arrived at Brundisium he would not wait for favourable weather, but at once crossed the sea, not without suffering a considerable loss in ships. The rest of his journey he performed by land. When passing through Galatia he was entertained by the prince of that country, Deiotarus, then a very old man. Deiotarus was busy building a city, and Crassus jestingly marvelled that at such an age he should engage in such an undertaking. "And you," replied the old man, "who are on your way to Parthia, are not quite in your youth." Crassus was sixty, and looked, we are told, considerably older.

His first operations, after his arrival, were fairly successful, but he did not make a favourable impression. The Euphrates he crossed without opposition, and he received the submission of some important towns in Mesopotamia. He was considered, on the other hand, to have been wanting in dignity when he allowed his soldiers to salute him on the field as Imperator after the capture of a third-rate fortress—for this was a compliment that was appropriate only to real achievements. And in his proceedings generally he seemed to look to the collection of wealth rather than to military glory. The tokens of ill-fortune to come were, of course, not wanting. Crassus had been joined by his son, who had been serving as one of Cæsar's lieutenants in Gaul, and both paid a visit to a famous temple at Hierapolis. As they were leaving it the son caught his foot and fell, and the elder man stumbled over him. The enemy were in no submissive mood. Envoys from the Parthian king declared that if Crassus was executing the will of the Roman people the Parthians would avenge the insult to the utmost, but that if he was only seeking his own private ends they would pardon an old man's folly and restore unharmed the garrisons who were virtually their prisoners. Crassus replied that he would give them an answer at Seleucia, their capital. "Seleucia!" cried the leader of the embassy, holding up the palm of his hand. "Hair will grow on this before you see Seleucia." The army soon became seriously discouraged. The Parthians were evidently a more formidable enemy than they had yet encountered, very different from the unwarlike races of Western Asia. The reports of the soothsayers were of the gloomiest kind, and omens of coming disasters were frequent. The spot selected for a camp was twice struck by lightning; when the rations were distributed the articles first given out were lentils and salt, the two chief articles in the meals served for the spirits of the dead. Worst of all, the eagle-standard of the legion that was the first to advance was seen to turn away from the enemy's country.

Crassus had under his command no contemptible force—seven legions, 4,000 cavalry, and an equal number of light-armed troops. The first reports that reached him represented the enemy as shrinking from the contest. This notion was confirmed by an Arab chief, Abgarus of Edessa, who was believed to be friendly to Rome. He had certainly done good service to Pompey, but he was now acting in the interest of the Parthian king. He urged on Crassus an immediate advance; the enemy, he declared, were already removing their most valuable property to a place of safety. This was all false. The Parthian king with half his army was ravaging Armenia; his commander-in-chief had been detached with the other half to deal with Crassus. The Romans moved forward with all the haste that they could compass. Day after day they advanced, but no enemy could be seen. At last some horsemen were descried in the distance, and Abgarus was sent on in advance to reconnoitre. He did not return, and the army again moved forwards. Their march brought them to a river called the Balissen. Crassus was advised by his staff to halt and encamp. He was too impatient to listen to this counsel, and still advanced. It was not long before he came in sight of the enemy. At first sight the Parthian host did not seem very formidable. It did not display any of the pomp and circumstance of war, and its numbers had been carefully concealed. Then by a sudden movement the banners of glistening silk embroidered with gold were displayed, and the helmets and coats of mail glittered in the sun, the drums giving out all the time a terrific volume of sound. Never before had the Romans encountered a similar enemy. It was a host of cavalry which they had to meet, most of them archers, both man and horse being protected with armour made sometimes of iron, sometimes of leather. The Romans were taken at a terrible disadvantage. All their tactics, especially the close order in which they were accustomed to fight, told against them, whilst their light-armed troops were hopelessly outnumbered.

The younger Crassus was sent forward by his father with a picked force, in the hope that he might relieve the legions of the brunt of the attack. The enemy retreated before him, but when they had lured him on out of sight or reach of the main army they turned upon him. He had no choice, so overwhelming were their numbers, but to fall back before them. He made a stand at a hill, on the sloping side of which he ranged what troops remained to him. But the ranks rising one above another offered a broader target to the Parthian archers. Nearly the whole force perished, Crassus and his officers by their own hands. Five hundred were taken prisoners; none escaped. The first knowledge that the elder Crassus had of his son's fate was the sight of his head on a pole. The attack upon the legions was renewed again and again until darkness brought a temporary relief. During the night the Romans retreated, and reached Carrhæ in safety. But even then their troubles were not ended. Crassus either would not or could not stay at Carrhæ, and set out in the hope of reaching the friendly country of Armenia. He was overtaken, and consented to hold a conference with the Parthian commander to discuss the terms of an armistice. It is not clear whether the Parthians intended treachery; anyhow the Romans suspected it. A fierce quarrel ensued; the Roman officers were killed, and Crassus put an end to his own life. Of the army many were taken prisoners, and a few contrived to escape. But as a force it ceased to exist.

The battle of Carrhæ, as it may be called, though it happened at some distance from that town, was one of the worst disasters in Roman history. What especially touched the pride of the Empire was the submission of the numerous prisoners to their fate. Horace inveighs against the cowardice of the men who were content to forget all the glorious associations of Rome and to become the subjects of a barbarian king. He seeks to console himself by telling how the standards captured from the army of Crassus were torn down from the Parthian temples by the victorious Augustus. What really happened was that these trophies were given up under the conditions of a peace made between Parthia and Rome. There was more than one struggle between the two powers, and the superiority of Roman arms was vindicated more than once. Parthia, also, had its triumphs. One Roman Emperor, Valerian, ended his days in Parthian captivity. When the Empire fell in the third century of our era it was by a rebellion among its own subjects.