Taken by the Enemy by Oliver Optic

Percy Pierson retained his position on the rail when his brother the major came up the gangway steps, which had been put over for him. As the latter went up, he could not help seeing him; and his astonishment evidently mounted to the highest degree, as manifested in his expression. The owner and the commander stood near the rail, to give the visitor a pleasant reception.

But the major took no notice of them; for his attention was plainly absorbed in his surprise at seeing his brother, dressed in uniform, on the rail of the steamer. He halted as soon as he had mounted the rail, over which he must pass to reach the deck. He looked at Percy for some time, without being able to say a word, and seemed to be not quite sure that it was he.