2773737 Fort Warren, Boston Harbour, where Messrs Mason and Slidell, the Captured Confederate Commissioners, are confined (engraving) by English School, (19th century); Private Collection; (add.info.: Fort Warren, Boston Harbour, where Messrs Mason and Slidell, the Captured Confederate Commissioners, are confined. Illustration for the Illustrated Times, 28 December 1861.); Look and Learn / Illustrated Papers Collection; English, out of copyright.