The Aetolians, bitterly disappointed at the peace which Flamininus had imposed on Greece and at his casual treatment of themselves, sought relief by trying to combine the three kings, Philip, Nabis and Antiochus, against Rome (summer 193). Antiochus received their overtures, but did not seem disposed to take immediate action. Philip rebuffed them; he remembered how they had urged the Romans to overthrow his kingdom. Nabis, however, responded, but too quickly. Breaking his treaty with Rome he fell on the freed towns of the Laconian coast. The Achaeans under Philopoemen denounced Nabis’ conduct to Rome and then defeated him in battle and blockaded Sparta.6 The Romans sent a small squadron to operate against Nabis, while during the winter Flamininus went to Greece to bring his personal influence to bear; he was soon joined by Eumenes. He quickly ended the war in the Peloponnese on the basis of the status quo (spring 192). Nabis was lucky to have escaped so lightly, but the Achaeans were disappointed at not being allowed to press home their victory.
Despite the failure of their ambitious coalition the Aetolians continued on their course, buoyed up by the hope of winning Demetrias, where considerable opposition had been shown to Flamininus who had accomplished a disquieting journey through Greece. Further, Antiochus now seemed ready to take action, and his envoy announced that he was willing to join the Aetolians in restoring Greek freedom (March 192). They then formally asked him to deliver Greece and to settle their quarrel with Rome. Thus Antiochus could now play the same rôle of liberator to the cities of Greece as Rome had to the Greek cities of Asia: not yet by open war, but by armed mediation. This alarmed Rome. She hurriedly prepared 70 quinqueremes to protect Sicily and to form a reserve; an army was sent from Bruttium to Brundisium and an emergency force was levied. But while Rome prepared and Antiochus delayed, the Aetolians acted. They proposed to seize Demetrias and Chalcis to facilitate Antiochus’ landing and to occupy Sparta in order to check the Achaeans. At Sparta they succeeded in assassinating Nabis, but were soon defeated and massacred; as a result Sparta was driven into the arms of the Achaean League. At Chalcis they failed completely. But they won Demetrias, and could thus offer Antiochus a secure base. But they had alienated Philip still more, for he had long coveted Demetrias. After further hesitation Antiochus landed a detachment of his army at Demetrias and marched to Lamia (autumn 192).
War, though not formally declared, was now inevitable. Antiochus, however, was not ready; he had only started preparing during the previous year, and it was a long task to mobilize the resources of his vast empire. But now that the Aetolians had precipitated the crisis, he must face a war which he did not really want. He was not going to fight in Greece from lust of conquest, nor even merely to assert his rights in Thrace. He desired that Rome should recognize him as an equal, and that he should be permitted to maintain his empire unhampered, and to develop it freely and in peace. To this end he had constantly tried to obtain friendship with the Romans, who failed to believe in the sincerity of his intentions and feared his increasing activity. To his offer of friendship they had replied by demands, unaccompanied by any concessions; that is, they insisted on asserting their superiority, not from militaristic aims but because they feared that the king, if recognized as an equal, would not be content to remain as such. Antiochus’ aims were reflected in his method of war.7 He did not wish to destroy Rome, but merely to make a military demonstration which would lead to his recognition as an equal power. Thus he rejected any idea of invading Italy, and while perhaps countenancing Hannibal’s plan for Carthaginian co-operation he turned to a limited offensive in Greece. Here he could challenge Rome’s supremacy with some prospect of success. If this was not immediately forthcoming he might hope that the Romans would tire of a long war in which their interests did not warrant great sacrifice. And even if they gained the upper hand they would hardly seek to destroy him root and branch: they had not pushed the First Punic War or their contest against Philip to this extreme. Thus he might hope for the success of his limited project, but he underestimated the perseverance and the distrust of Rome.
Although the smallness of the force with which the new liberator of the Greeks appeared caused much disappointment, he was somewhat grudgingly elected generalissimo by the Aetolians. Disturbances in his favour in many towns were soon checked. For instance, trouble at Athens was calmed by the presence of Flamininus and perhaps of Eumenes, supported by the eloquence of another Roman legate, M. Porcius Cato, who had advanced the Roman cause in Patrae, Aegium and Corinth. Antiochus was rebuffed by Chalcis and Boeotia, and in November Flamininus succeeded in persuading the Achaean League to declare war on the king and his Aetolian allies. But while Antiochus was busy storming Chalcis, a body of 500 Roman troops marching thither from the fleet on the Boeotian coast was attacked and almost annihilated by one of his generals at Delium. This act may have been justified from the military and legal point of view – for Rome’s allies, the Achaeans, had now declared war on him – but Antiochus could no longer pretend that he had come to liberate the Greeks without fighting Rome. Further, now that he was technically the aggressor, Rome could start the war before it was formally declared by a vote of the people. Antiochus at last captured Chalcis so that the rest of Euboea and Boeotia went over to him. Then he conducted a successful campaign against Thessaly as far as Larissa, but the appearance of a Roman detachment at Gonni led him to suspend operations in January 191. The dramatic appearance of this Roman force was a severe blow: it revealed that Rome had entered the war and that Philip was siding with Rome, for only with Philip’s consent could the troops have come through his country. Rome had in fact secured the support of Philip by promising that he might keep Demetrias and any other Thessalian cities which he took from the Aetolians. Hannibal was said to be urging Antiochus to a larger view: his son Seleucus should attack Macedon through Thrace to prevent Philip’s co-operation with Rome; part of the fleet should attack the west coast of Italy, while part hindered the Romans crossing to Greece; Antiochus should advance to Apollonia to protect Greece and to seem ready to invade Italy. If ever Hannibal formulated this plan or hoped that Antiochus would follow it, his hopes were now effectively broken by Philip’s declaration of friendship with Rome. The war must now be fought in Greece.
Realization of this affected the plans of Rome also. In the autumn of 192 a praetor named Baebius had crossed from southern Italy to Apollonia with only a few troops; until Antiochus’ plans were known a large force could not be sent, as reserves must be held in Italy in case of diversions in Africa, Sicily or even Italy. But when Philip, actuated by self-interest and jealousy of Antiochus, had shown his hand, Rome could proceed with more energy and the Roman people formally declared war (at the beginning of the consular year 191, which by the Julian calendar was about November 192). Antiochus, however, had made the best of his opportunities. He held Demetrias and Chalcis, the whole of central Greece except Attica and Acarnania, and the greater part of Thessaly. Early in 191 he attacked Acarnania, but was soon recalled to Thessaly.
The consul M’. Acilius Glabrio landed at Apollonia with 22,000 troops in February 191, and was enabled to march at once towards Thessaly by reason of the mildness of the season and the preparations already made by Baebius and Philip. As town after town capitulated he gradually wrested all Thessaly from Antiochus. The king had received few reinforcements from Asia, while the Aetolians only sent 4,000 men; he was thus forced to fall back on Thermopylae which guarded the road to central Greece. In the famous pass he took up a position, not in the middle as Leonidas had done against the Persians, and the united Greeks against the Gauls in 279, but at the eastern gate where the sea was considerably further from the mountains than it had been in 480 BC. He strengthened his position by an earth rampart and a wall, and protected his flank by stationing half the Aetolians at Heraclea and the other half at the three forts guarding the mountain track by which the pass could be turned.8 Acilius, who camped in the middle of the pass, launched a frontal attack but was easily beaten back, while the Aetolian force at Heraclea threatened his rear. But the inadequacy of the Aetolian contingent enabled the Romans to repeat the exploit of the Persian Hydarnes. Two ex-consuls, who were serving in the army, made the attempt by night. Valerius Flaccus, who advanced up the eastern track to join the main route over the mountains, was unable to pass the two forts. But Cato, taking the longer western route, swept past the defenders of the Callidromos path, where the Phocians had fled before the Persians three centuries earlier, and descended on the rear of the enemy’s main army. The defeat was complete. Unlike Leonidas, Antiochus rode off, and collecting the panic-stricken survivors retired to Chalcis. Thence he set sail for Ephesus. The half-hearted support of his Aetolian allies and the slowness of his own mobilization thwarted his attempt to fight out the Syrian War in Europe. At one blow the Romans had driven their dreaded opponent from Greece.
The settlement of Greece was carried through the same year. Phocis, Boeotia, Ghalcis and Euboea surrendered to Rome at once, but Aetolia remained obdurate. Acilius determined not merely to impose a peace on the Aetolians, from which they might recover to cause continued trouble, but to strike at the very roots of their power. When Heraclea, which commanded Thermopylae and had enabled the Aetolians to cut communications between northern and central Greece, was stormed by Acilius, the Aetolians sought peace, but they were offered such harsh terms that they determined to resist. Acilius struck a shrewd blow by laying siege to Naupactus, their principal port in the Corinthian Gulf. But such harshness was unwise, for it unduly benefited Philip, who was steadily regaining his power in the north, and it destroyed the ideal of a free Greece. Further, as a war of sieges must necessarily be protracted, it gave Antiochus longer to recover before Rome could square accounts with him. Flamininus, who meanwhile had been checking the cupidity of the Achaeans and imposing unity in the Peloponnese, ended hostilities in Aetolia by demonstrating to Acilius that the destruction of Aetolia involved the aggrandisement of Philip. He thus won for the Aetolians permission to appeal to the Senate and struck a blow at Antiochus, who still hoped for Aetolian co-operation.