American Civil War, Pittsburgh
... that during the American Civil War, Pittsburgh made the world's first 21-inch caliber gun?
... that during the <b id="mwFOU"><a href="./Pittsburgh_in_the_American_Civil_War" id="mwFOY" rel="mw:WikiLink" title="Pittsburgh in the American Civil War">American Civil War, Pittsburgh</a></b> made the world's first 21-inch <a href="./Caliber" id="mwFOc" rel="mw:WikiLink" title="Caliber">caliber</a> <a href="./Artillery" id="mwFOg" rel="mw:WikiLink" title="Artillery">gun</a>?