In Greek mythology, Promachus (Ancient Greek Πρόμαχος, "champion" or "who leads in battle") son of Parthenopaeus is one of the Epigoni who march on Thebes a generation after the Seven. Apollodorus lists him in the muster-roll; Pausanias records that he died in the attack and was buried near Teumessus, and that the victors were commemorated at Delphi.
Adapted from Wikipedia, "Promachus" · CC BY-SA 4.0
I.The Epigoni
Promachus is son of Parthenopaeus, the Arcadian (or Biantid) captain among the Seven against Thebes. A generation later the sons of the Seven — the Epigoni — renew the war under Alcmaeon's leadership. Apollodorus counts Promachus beside Alcmaeon and Amphilochus, Aegialeus, Diomedes, Sthenelus, Thersander, and Euryalus.
Pausanias says Promachus died in the attack on Thebes and was buried nearby at Teumessus. The successful Epigoni were commemorated among the statues at Delphi.
II.Genealogy notes
Apollodorus' catalogues are not wholly consistent on Parthenopaeus' own parentage — Arcadian son of Atalanta in one place, Biantid son of Talaus in another — but both strands give him a son Promachus among the avengers. The atlas node follows the Epigonus who dies at Thebes, not the infant brother of Jason or the Ithacan suitor.
III.Homonyms
This atlas entry (promachus-epigoni) is Parthenopaeus' son among the Epigoni. He is distinct from Promachus son of Aeson (Jason's brother slain by Pelias), from the Boeotian warrior killed by Acamas in the Iliad, from Heracles' son by Psophis, from the Ithacan suitor (promachus-ithaca), and from the Knossian lover of Leucocomas.