Titus Livius (Livy), The History of Rome, Book 37
William A. McDevitte, Sen. Class. Mod. Ex. Schol. A.B.T.C.D., Ed.

18. In the mean time Seleucus, son of Antiochus, who had [2??] kept his army in Aetolia, through the whole of the winter employed, partly, in succouring his allies, partly, in ravaging the [p. 1674]lands of those whom he could not seduce to his side, resolved to make an incursion on the territory of king Eumenes, while he, at a great distance from home, was assisting the Romans and Rhodians, in attacks on the maritime parts of Lycia. [3] He advanced with hostile standards, first, to Elaea; afterwards, the design of besieging it being given up, having wasted the country in a hostile manner, he led his army to lay siege to Pergamus, the capital and principal fortress of the kingdom. [4] Attalus, at first, posting advanced guards outside the city, and sending out parties of cavalry and light infantry, harassed rather than withstood the enemy. [5] But, after some time, having discovered, in slight skirmishes, that he was not a match for the enemy in any respect, he drew back his men within the fortifications, and then the city began to be besieged. [6] About this time, Antiochus, leaving Apamea with a vast army compounded of various nations, encamped first at Sardis, and afterwards took post at a small distance from the camp of Seleucus, at the head of the river Caicus. [7] The most formidable part of his force was a body of four thousand Gauls, procured for hire: these, with a few others intermixed, he detached, with orders to waste utterly the country about Pergamus. [8] When news of these transactions arrived at Samos, Eumenes being thus recalled by a war in his own dominions, sailed with his fleet to Elaea; and finding there, in readiness, some light troops of horse and foot, he took them for an escort, and proceeded directly to Pergamus, before the enemy could be apprised of his arrival, or could put themselves in motion. [9] Then again skirmishes began to take place in the sallies, Eumenes undoubtedly shrinking from the risk of a decisive engagement. In a few days after the combined fleet of the Romans and Rhodians came from Samos to Elaea, to support the king. [10] When information was brought to Antiochus that these had landed troops at Elaea, and that so many fleets were assembled in one harbour, and at the same time heard that the consul, with his army, was already in Macedonia, and that the things that were necessary for the passage of the Hellespont were being prepared, he judged that now was the time for negotiation, before he should be pressed on sea and land at once; [11] and with this view he chose for his camp a rising ground opposite to Elaea. [12] Leaving there all the infantry, with his cavalry, amounting to six thousand, he [p. 1675]went down into the plains, which lay under the walls of the town, having despatched a herald to Aemilius, to acquaint him that he wished to treat of peace.