Thus it would seem that every thing was settled. There was, however, one difficulty still remaining. Arsinoe, the widow of Lysimachus, still lived. It was Arsinoe, it will be recollected, whose jealousy of her half-sister, Lysandra, had caused the death of Agathocles and the flight of Lysandra, and which had led to the expedition of Seleucus, and the subsequent revolution in Macedon. When her husband was killed, she, instead of submitting at once to the change of government, shut herself up in Cassandria, a rich and well-defended city. She had her sons with her, who, as the children of Lysimachus, were heirs to the throne. She was well aware that she had, for the time being, no means at her command for supporting the claims of her children, but she was fully determined not to relinquish them, but to defend herself and her children in the city of Cassandria, as well as she was able, until some change should take place in the aspect of public affairs. Ceraunus, of course, saw in her a very formidable and dangerous opponent; and, after having triumphed over Antigonus, and concluded his peace with Antiochus and with Pyrrhus, he advanced toward Cassandria, revolving in his mind the question by what means he could best manage to get Arsinoe and her children into his power.
He concluded to try the effect of cunning and treachery before resorting to force. He accordingly sent a message to Arsinoe, proposing that, instead of quarreling for the kingdom, they should unite their claims, and asking her, for this purpose, to become his wife. He would marry her, he said, and adopt her children as his own, and thus the whole question would be amicably settled.
Arsinoe very readily acceded to this proposal. It is true that she was the half-sister of Ceraunus; but this relationship was no bar to a matrimonial union, according to the ideas that prevailed in the courts of kings in those days. Arsinoe, accordingly, gave her consent to the proposal, and opened the gates of the city to Ceraunus and his troops. Ceraunus immediately put her two sons to death. Arsinoe herself fled from the city. Very probably Ceraunus allowed her to escape, since, as she herself had no claim to the throne, any open violence offered to her would have been a gratuitous crime, which would have increased, unnecessarily, the odium that would naturally attach to Ceraunus's proceedings. At any rate, Arsinoe escaped, and, after various wanderings, found her way back to her former home in her father's court at Alexandria.