He was wrong.
I’m pretty sure this is wrong. In French, one doesn’t say ‘I am wrong’ but ‘I have wrong’, ie. ‘avoir tort’ not ‘etre tort’ (apologies I cannot type accents on this keyboard). To say he was wrong in the past is therefore ‘Il avait tort’ or ‘Il a eu tort’ (depending on the exact case).
The French sentence is “Il eut tort”, right? “Eut” is the third-person singular form of “avoir” in the passé composé.
Exact, but this is passé simple, not passé composé.
Passé simple: “Il eut tort.”
Passé composé: “Il a eu tort.”
I realized afterwards that I had written the wrong thing and came back to fix it, but you got here first, @Neykah.