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.
Roman successes in Greece
 While these things were going on in the city, Manius received the supplications of the Phoceans, the Chalcideans, and others who had cooperated with Antiochus, and he relieved their fears. He and Philip ravaged Aetolia and reduced its cities. He captured, in hiding, Democritus, the general of the Aetolians, who had threatened Flamininus that he would pitch his camp on the banks of the Tiber.
Manius, with an army laden with baggage and spoils, made his way to Callipolis over Mount Corax, the highest, rockiest, and most difficult in that region. Many soldiers, by reason of the badness of the road, fell over precipices and were dashed in pieces with their arms and accouterments. Although the Aetolians might have punished them severely, they were nowhere to be seen, having sent an embassy to Rome to treat for peace.
In the meantime Antiochus ordered the satraps of upper Asia to send their army down to the coast in all haste, and he fitted out a fleet which he put under the command of Polyxenidas, an exile from Rhodes. He crossed over to Chersonesus and again fortified it. He also strengthened Sestus and Abydus, through which the Roman legions would be obliged to pass if they should invade Asia.note[Abydus (modern Çanakkale) and Sestus (Eceabat) were the usual places to cross the Hellespont. The strait is here very narrow and can even be bridged.] He made Lysimacheia his principal magazine for the present war and accumulated large supplies of arms and provisions in it, believing that the Romans would presently attack him with large land and sea forces.
The latter appointed Lucius Scipionote[Lucius Cornelius Scipio.] as the successor of Manius in the command, as he was then consul, but as he was inexperienced in war they appointed as his lieutenant his brother, Publius Scipio, who had humbled the Carthaginian power and who first bore the title of Africanus.
 While the Scipios were still making their preparations,note[191 BCE.] Livius, who had charge of the coast defense of Italy and who had been chosen the successor of Atilius, with his own coast-guard ships and some contributed by the Carthaginians and other allies, sailed for Piraeus.note[The port of Athens.] Receiving there the fleet from Atilius he set sail with eighty-one decked ships, Eumenes following with fifty of his own, one-half of which had decks. They put in at Phocaea, a place belonging to Antiochus, but which received them from fear, and on the following day they sailed out for a naval engagement.
Polyxenidas, commanding the fleet of Antiochus, met them with 200 ships much lighter than those opposed to him, which was a great advantage to him, since the Romans were not yet experienced in nautical affairs. Seeing two Carthaginian ships sailing in front, he sent three of his own against them and took them, but found them empty, the crews having leaped overboard.
Livius dashed angrily at the three with his flag-ship, much in advance of the rest of the fleet. The enemy being three to one grappled him contemptuously with iron hooks, and when the ships were fastened together the battle was fought as though it were on land. The Romans, being much superior in valor, sprang upon the enemy's ships, overpowered them, and returned, bringing back two ships captured simultaneously by one.
This was the prelude to the naval engagement. When the fleets came together the Romans had the best of it by reason of their bodily strength and bravery, but on account of the unwieldy size of their ships they could not capture the enemy, who got away with their nimble craft, and, by rapid flight, took refuge in Ephesus.
The Romans repaired to Chios, where twenty-seven Rhodian ships joined them as allies. When Antiochus received the news of this naval fight, he sent Hannibal to Syria to fit out another fleet from Phoenicia and Cilicia. When he was returning with it the Rhodians drove him into Pamphylia, captured some of his ships, and blockaded the rest.
The Romans invade Asia
 In the meantime Publius Scipio arrived in Aetolia with the consul and received the command of the army from Manius.note[190 BCE.] He scorned the siege of the Aetolian towns as small business, and allowed the imploring people to send a new embassy to Rome, while he hastened against Antiochus before his brother's consulship should expire.
He moved by way of Macedonia and Thrace to the Hellespont, and it would have been a very hard march for him had not Philip of Macedonia repaired the roads, entertained him, escorted him, bridged the streams some time before, and furnished him provisions. In return for this the Scipios immediately relieved him from the payment of the remaining money indemnity, having been authorized to do so by the Senate if they should find him zealous.note[This subject matter is also treated by Appian in the Macedonian Wars §14.]
They also wrote to Prusias, king of Bithynia, reminding him that the Romans were in the habit of augmenting the possessions of the kings in alliance with them. They said that, although they had conquered Philip of Macedonia, they had allowed him to retain his kingdom, had released his son whom they had held as a hostage, and had remitted the money payment still due. Thereupon Prusias willingly entered into alliance with them against Antiochus.
Livius, the commander of the fleet, when he learned that the Scipios were on the march, left Pausimachus, the Rhodian, with the Rhodian ships and a part of his own, in Aeolis, and himself sailed with the greater part to the Hellespont to assist the army. Sestus and Rhoeteum, and the harbor of the Achaeans,note[This was the place where the Achaeans landed before they attacked Troy.] and several other places surrendered to him. Abydus refused and he laid siege to it.
 After the departure of Livius, Pausimachus trained his sailors by repeated exercises, and constructed machines of various kinds. He attached iron pans containing fire to long poles and suspended them over the sea, so as to clear his own ships and fall upon those of the enemy when they approached.
While he was thus engaged Polyxenidas, the admiral of Antiochus, who was also a Rhodian, but had been banished for crime, laid a trap for him. He promised to deliver the fleet of Antiochus to him if he would agree to help him in securing readmittance to his own country. Pausimachus suspected the wily rascal and took special pains to guard against him. But after Polyxenidas had written him an autograph letter on the subject of the betrayal and in accord therewith had sailed away from Ephesus on the pretense of procuring grain for the army, Pausimachus, observing the movement and thinking that no one would put his own signature to a letter proposing a betrayal unless he was speaking the truth, felt entire confidence, relaxed his vigilance, and sent his own fleet away to procure corn.
Polyxenidas, seeing that his stratagem was successful, reassembled his ships, and sent the pirate Nicander to Samos with a few men to create confusion by getting in the rear of Pausimachus on the land, and himself sailed at midnight, and about daybreak fell upon him while still asleep.
Pausimachus, in this sudden and unexpected catastrophe, ordered his men to abandon their ships and defend themselves on land. When Nicander attacked him in the rear he thought that the land had been taken possession of by night not merely by those who were visible, but by a much larger number. So he made another confused rush for his ships. He was foremost in the encounter and the first to fall, fighting bravely. The rest were all captured or killed. Seven of the ships, which were provided with the fire-apparatus, escaped, as no one dared approach them for fear of conflagration. The remaining twenty Polyxenidas towed to Ephesus.
 Upon the news of this victory Phocaea again changed sides to Antiochus, as did also Samos and Cyme. Livius, fearing for his own ships, which he had left in Aeolis, returned to them in haste. Eumenes hastened to join him, and the Rhodians sent the Romans twenty new ships. In a short time they were all in good spirits and they sailed toward Ephesus prepared for another engagement. As no enemy appeared they divided their naval force into two parts, one half for a long time showing itself on the high sea, while the other landed on the enemy's coast and ravaged it until Nicander attacked them from the interior, took away their plunder, and drove them back to their ships. Then they withdrew to Samos, and Livius' term of office as admiral expired.