Plutarch, Pyrrhus
Bernadotte Perrin, Ed.

10. After this battle Pyrrhus returned to his home rejoicing in the splendour which his fame and lofty spirit had brought him; and when he was given the surname of ‘Eagle’ by the Epeirots, ‘Through you,’ he said, ‘am I an eagle; why, pray, should I not be? It is by your arms that I am borne aloft as by swift pinions.’ But a little while after, learning that Demetrius was dangerously sick, he suddenly threw an army into Macedonia, intending merely to overrun and plunder some parts of it. [2] Yet he came within a little of mastering the whole country and getting the kingdom without a battle; for he marched on as far as Edessa without opposition from anyone, and many actually joined his forces and shared his expedition. And now Demetrius himself was roused by the peril to act beyond his strength, while his friends and commanders in a short time collected many soldiers and set out with zeal and vigour against Pyrrhus. Pyrrhus, however, had come more for plunder than anything else, and would not stand his ground, but fled, losing a part of his army on the march, under the attacks of the Macedonians.

[3] However, because Demetrius had easily and speedily driven Pyrrhus out of the country, he did not leave him to his own devices, but now that he had determined to undertake a great enterprise and to recover his father's realm with a hundred thousand soldiers and five hundred ships, he did not wish to have collisions with Pyrrhus, nor yet to leave behind in him an enterprising and troublesome neighbour for the Macedonians. He wished, rather, since he had no time to wage war against Pyrrhus, to come to terms and make peace with him, and then turn his arms against the other kings. [4] But after an agreement had been made between them for these reasons, the purpose of Demetrius became apparent, as well as the magnitude of his preparations, and the kings, in alarm, kept sending to Pyrrhus messengers and letters,¹ expressing their amazement that he should let slip his own opportunity for making war and wait for Demetrius to seize his; and that when he was able to drive Demetrius out of Macedonia, since he was now much occupied and disturbed, he should await the time when his adversary, at his leisure and after he had become great, could wage a decisive struggle with him for the sanctuaries and tombs of the Molosian land, an adversary who had just robbed him of Corcyra, and his wife besides. [5] For Lanassa, who found fault with Pyrrhus for being more devoted to his barbarian wives than to her, had retired to Corcyra, whither, since she desired a royal marriage, she invited Demetrius, understanding that he, of all the kings, was most readily disposed to marry wives. So Demetrius sailed thither, married Lanassa, and left a garrison in the city.