After Cassander's death, the eldest of his sons, Philip, reigned for a short time over the Macedonians and then died, and the two remaining brothers quarrelled with one another over the succession. One of them, Antipater, murdered his mother, Thessalonicé, and the other, Alexander, summoned to his help Pyrrhus from Epeirus, and Demetrius from Peloponnesus.
Edition :
Plutarch. Plutarch's Lives. with an English Translation by. Bernadotte Perrin. Cambridge, MA. Harvard University Press. London. William Heinemann Ltd. 1920. 9.
Remark :
date: The date is taken from the New Pauly.
http://referenceworks.brillonline.com/entries/brill-s-new-pauly/thessalonica-e1210990 long-term consequence: Alexander is killed by Demetrius' guards after he sent for his help. This is mentioned in 36.6.