ἐκπολεμεῖν
From LSJ
ὣς ὁ μὲν ἔνθ' ἀπόλωλεν, ἐπεὶ πίεν ἁλμυρὸν ὕδωρ → so there he perished, when he had drunk the salt water
Lexicon Thucydideum
bello petere, bellum inferre, to attack in war, make war on, 6.91.5,
PASS. hostis fieri, to become an enemy, 8.57.1, [Vat. Bekk. Goell. Did. Vatican Bekker Goeller Dindorf edition ἐκπεπολεμῶσθαι].