expression, ichidan verb
win the battle but lose the war; fail at the last moment despite an advantage
Idiomatic expression originating from sumo: you may dominate in technique (win the sumo) but still lose the match (lose the contest). Used broadly for situations where tactical success does not lead to overall victory, or when a favorable position is squandered at the end.
In negotiations, even if you win on small points, if you lose the contract in the end, it's a case of winning the battle but losing the war.
彼は議論では優勢だったが、結論でミスをして相撲に勝って勝負に負けた。
He had the upper hand in the debate, but made a mistake in the conclusion and ended up winning the battle but losing the war.