Charles Ellicott Commentary Acts 23:27

"This man was seized by the Jews, and was about to be slain of them, when I came upon them with the soldiers and rescued him, having learned that he was a Roman." — Acts 23:27 (ASV)

Then I came with an army.—Better, with my troops. The chief captain ingeniously colors his statement to claim credit for rescuing a Roman citizen, although, in fact, he did not discover that he was a citizen until he was about to scourge him without a trial. That fact, of course, is passed over without a word.