1 The estimate of the period of Achaios’s birth is based on his coin portraits which show a man about 35 to 50 years old. See, for example, the following tetradrachm (photo courtesy of Freeman & Sear – Gemini Numismatic Auctions, Auction I, Lot 204, January 2005):

Note that his portrait is known only from very rare silver tetradrachms (see Houghton and Lorber, SC I, 953 and Ad199-200; the coin Ad199 is shown on the photo above) and from a unique gold stater (see Houghton and Lorber, SC I, 952 = Newell, WSM, 1439).

2 These dates are taken from Houghton and Lorber, Seleucid Coins, A Comprehensive Catalogue. Part I, Vol. 1, p. 347 (they refer to John Ma, Antiochos III and the Cities of Western Asia Minor, Oxford, 1999). According to Grainger, A Seleukid Prosopography and Gazetteer, p. 5 - Achaios (1), he reigned as King from 221 to 213 BC. Green, Alexander to Actium, pp. 293 and 734, gives him the regnal period from 220 to 213 BC.

3 Polybios, Histories (the Loeb edition), 8.20.7-10 and 8.21.1-4: He (Achaios) was very soon surrounded on all sides and found himself in the hands of his enemies, who at once led him and his friends off to Antiochus (Antiochos III). The king, who had long been waiting the issue in a fever of excitement, had dismissed his usual suite and remained awake in his tent attended only by two or three of his bodyguard. When Cambylus (the commander of the Cretans in Antiochos III’s army) and his men entered and set down Achaeus on the ground bound hand and foot, Antiochus was so dumbstruck with astonishment that for a long time he remained speechless and at last was deeply affected and burst into tears, feeling thus, as I suppose, because he actually saw how hard to guard against and how contrary to all expectation are events due to Fortune. [...] But when at dawn the king’s friends flocked to his tent, as was the custom, and saw the thing with their own eyes, they were in the same case as the king himself had been; for they were so astonished that they could not credit their sense. At the subsequent sitting of the Council, there were many proposals as to the proper punishment to inflict on Achaeus, and it was decided to lop off in the first place the unhappy prince’s extremities, and then, after cutting off his head and sewing it up in an ass’s skin, to crucify his body. When this had been done, and the army was informed of what had happened, there was such enthusiasm and wild excitement throughout the whole camp, that Laodice (Laodike, Achaios’ wife), who was alone aware of her husband’s departure from the citadel, when she witnessed the commotion and disturbance in the camp, divined the truth.

Polybios, Histories (the Macmillan edition), 8.22-23: Being thus quickly surrounded on every side, Achaeus (Achaios) fell into the hands of his enemies, and along with his four friends was taken straight off to Antiochus (Antiochos III). The king was in his tent in a state of extreme anxiety awaiting the result. He had dismissed his usual court, and, with the exception of two or three of the bodyguard, was alone and sleepless. But when Cambylus (the commander of the Cretans in Antiochos III’s army) and his men entered, and placed Achaeus in chains on the ground, he fell into a state of speechless astonishment: and for a considerable time could not utter a word, and finally overcome by a feeling of pity burst into tears; caused, I have no doubt, by this exhibition of the capriciousness of Fortune, which defies precaution and calculation alike. [...] And, indeed, when at daybreak the king’s friends assembled as usual at his tent, and saw this strange spectacle, they too felt emotions very like those of the king; while extreme astonishment made them almost disbelieve the evidence of their senses. However the council met, and a long debate ensued as to what punishment they were to inflict upon Achaeus. Finally, it was resolved that his extremities should be cut off, his head severed from his body and sewn up in the skin of an ass, and his body impaled. When this sentence had been carried out, and the army learnt what had happened, there was such excitement in the ranks and such a rush of the soldiers to the spectacle, that Laodice (Laodike, Achaios’ wife) on the acropolis, who alone knew that her husband had left it, guessed what had happened from the commotion and stir in the camp.

4 Polybios, Histories (the Loeb edition), 4.51: ... for Andromachus was Achaeus’ (Achaios’) father and brother of Laodice the wife of Seleucus (Seleukos II).

Polybios, Histories (the Macmillan edition), 4.51: For Andromachus was not only father of Achaeus (Achaios), but brother also of Laodice, the wife of Seleucus (Seleukos II).

Polybios, Histories (the Loeb edition), 8.20: For Achaeus (Achaios) was the son of Andromachus the brother of Laodice the wife of Seleucus (of Seleukos II); he had married Laodice the daughter of King Mithridates (Mithridates II), ...

Polybios, Histories (the Macmillan edition), 8.22: For here was Achaeus (Achaios), a son of Andromachus, the brother of Seleucus’s (of Seleukos II) queen Laodice, and married to Laodice, a daughter of King Mithridates (Mithridates II), ...

Note that these English translations of the passage 8.20/8.22 (the Loeb and the Macmillan edition, respectively) suggest that Andromachos was the father of Laodike, the wife of Seleukos II. However, according to Passehl, personal communication, the original text is explicit that Andromachos was the father of Achaios and the brother of Laodike.

Note also that Grainger, A Seleukid Prosopography and Gazetteer, p. 5 - Achaios (1) and p. 8 - Andromachos, also states that Achaios was a nephew of Laodike, the wife of Seleukos II, but he is shown as her brother in Table 1 on p. 820.

5 Grainger, A Seleukid Prosopography and Gazetteer, p. 5 - Achaios (1) and p. 49 - Laodike (10); Bevan, The House of Seleucus, Vol. II, p. 1; Polybios, Histories, 8.20 (the Loeb edition) / 8.22 (the Macmillan edition) - see footnote 4 for quotations.