Although only his books on the Roman Civil Wars survive in their entirety, large parts of Appian's book on the Syrian War, or Syriaca, have also come down to us. This book deals with the war that the Romans and the Seleucid king Antiochus III the Great fought in 192-188, but also discusses, as an appendix, the history of the Seleucid Empire. The Syriaca is a valuable source for the history of the ancient Near East between the reign of Alexander the Great and the Roman conquest.
The translation was made by Horace White; notes by Jona Lendering.
Prelude to war
 Antiochus (the son of Seleucus and grandson of Antiochus), king of the Syrians, the Babylonians, and other nations, was the sixth in succession from that Seleucus who succeeded Alexander in the government of the Asiatic countries around the Euphrates. He invaded Media and Parthia, and other countries that had revolted from his ancestors, and performed many exploits, from which he was named Antiochus the Great. Elated by his successes, and by the title which he had derived from them,note[198 BCE.] he invaded Coele-Syrianote[Coele-Syria is a notoriously vague expression, derived from the Aramaic word kôl, "entire". Although it seems to have indicated modern Syria, Lebanon, Israel, and the Palestine territories, Appian uses it for southern Syria and northern Palestine. It was a well-known battleground for Seleucid and Ptolemaic armies.] and a portion of Cilicia and took them away from Ptolemy Philopator, king of Egypt, who was still a boy.
As there was nothing small in his views he marched among the Hellespontines, the Aeolians, and the Ionians as though they belonged to him as the ruler of Asia;note[197 BCE; "king of Asia" was the title of the Seleucid kings.] and indeed, they had been formerly subjects of the Asiatic kings. Then he crossed over to Europe,note[196 BCE.] brought Thrace under his sway, and reduced by force those who would not obey him.
He fortified Chersonesus and rebuilt Lysimacheia, which Lysimachus, who ruled Thrace in the time of Alexander, built as a stronghold against the Thracians themselves, but which they destroyed after his death. Antiochus repeopled it, calling back the citizens who had fled, redeeming those who had been sold as slaves, bringing in others, supplying them with cattle, sheep, and agricultural implements, and omitting nothing that might contribute to its speedy completion as a stronghold; for the place seemed to him to be admirably situated to hold all of Thrace in subjection, and a convenient base of supplies for other operations that he contemplated.
 Here the open disagreements between him and the Romans began, for as he passed among the Greek cities thereabout most of them joined him and received his garrisons, because they feared capture by him. But the inhabitants of Smyrna and Lampsacus, and some others who still resisted, sent ambassadors to Flamininus, the Roman general, who had lately overthrown Philip the Macedonian in a great battle in Thessaly; for the affairs of the Macedonians and of the Greeks were closely linked together at certain times and places, as I have shown in my Greek History.note[In the Second Punic War (218-202), king Philip V of Macedonia had sided with Carthage against Rome. When this war was over, the Romans invaded Greece; in 197, their commander Titus Quinctius Flamininus defeated Philip at Cynoscephalae in Thessaly.]
Accordingly, certain embassies passed between Antiochus and Flamininus and tested each other to no purpose. The Romans and Antiochus had been suspicious of each other for a long time, the former surmising that he would not keep quiet because he was so much puffed up by the extent of his dominions and the acme of fortune that he had reached. Antiochus, on the other hand, believed that the Romans were the only people who could put a stop to his increase of power and prevent him from passing over to Europe.
Still, there was no outward cause of enmity between them until ambassadors came to Rome from Ptolemy Philopator complaining that Antiochus had taken Syria and Cilicia away from him. The Romans gladly seized this occasion as one well suited to their purposes, and sent to Antiochus ostensibly to bring about a reconciliation between him and Ptolemy, but really to find out his designs and to check him as much as they could.
 Gnaeus, the chief of the embassy, demanded that Antiochus should allow Ptolemy, who was a friend of the Roman people, to rule over all the countries that his father had left to him, and that the cities of Asia that had been part of the dominions of Philip should be independent, for it was not right that Antiochus should usurp powers of which the Romans had deprived Philip. "We are wholly at a loss to know," he said, "why Antiochus should come from Media bringing such a fleet and such an army from the upper country to the Asiatic coast, make an incursion into Europe, build cities there, and subdue Thrace, unless these are the preparations for another war."
Antiochus replied that Thrace had belonged to his ancestors, that it had fallen away from them when they were occupied elsewhere, and that he had resumed possession because he had leisure to do so. He had built Lysimacheia as the future seat of government of his son Seleucus. He would leave the Greek cities of Asia independent if they would acknowledge the gratitude therefor as due to himself and not to the Romans. "I am a relative of Ptolemy," he said, "and I shall be his father-in-law, although I am not so now, and I will see to it that he renders gratitude to you. I am at a loss to know by what right you meddle with the affairs of Asia when I never interfere with those of Italy." And so they separated without coming to any understanding, and both sides broke into more open threats.
 A rumor having spread abroad that Ptolemy Philopator was dead, Antiochus hastened to Egypt in order to seize the country while bereft of a ruler. While on this journey Hannibal the Carthaginian met him at Ephesus. He was now a fugitive from his own country on account of the accusations of his enemies, who reported to the Romans that he was hostile to them, that he wanted to bring on a war, and that he could never enjoy peace. This was a time when the Carthaginians were leagued with the Romans by treaty.
Antiochus received Hannibal in a magnificent manner on account of his great military reputation, and kept him near himself. At Lycia he learned that Ptolemy was alive. So he gave up the idea of seizing Egypt and turned his attention to Cyprus, hoping to take it instead of Egypt, and sailed thither with all speed. Encountering a storm at the mouth of the river Sarus and losing many of his ships, some of them with his soldiers and friends, he sailed back to Seleucia in Syria to repair his damaged fleet. There he celebrated the nuptials of his children, Antiochus and Laodice, whom he had joined together in marriage.
 Now, determining no longer to conceal his intended war with the Romans,note[193 BCE.] he formed alliances by marriage with the neighboring kings. To Ptolemy in Egypt he sent his daughter Cleopatra, surnamed Syra, giving with her Coele-Syria as a dowry, which he had taken away from Ptolemy himself, thus flattering the young king in order to keep him quiet during the war with the Romans. To Ariarathes, king of Cappadocia, he sent his daughter Antiochis, and the remaining one to Eumenes, king of Pergamon.
But the latter, seeing that Antiochus was about to engage in war with the Romans and that he wanted to form a marriage connection with him on this account, refused her. To his brothers, Attalus and Philetaerus, who were surprised that he should decline marriage relationship with so great a king, who was also his neighbor and who made the first overtures, he showed that the coming war would be of doubtful issue at first, but that the Romans would prevail in the end by their courage and perseverance. "If the Romans conquer," said he, "I shall be firmly seated in my kingdom. If Antiochus is the victor, I may expect to be stripped of all my possessions by my powerful neighbor, or, if I am allowed to reign, to be ruled over by him." For these reasons he rejected the proffered marriage.