What if an Iowa-class hull replaced USS Iowa BB-4 at launch in 1896?
Short answerThe yard would struggle even to handle it, finishing it would be doubtful, and Britain would launch a major effort to build larger and more heavily armed ships.
NotesThe immediate problem is physical because William Cramp's Philadelphia facilities and waterways were not prepared for a BB-61-sized hull. Even if the bare hull could be moved, 1890s industry could not simply reproduce or finish its modern machinery, weapons, armour, and control systems. The United States might possess the world's largest hull without a practical route to making it a completed Iowa-class battleship. Britain would nevertheless react to its scale, potentially accelerating larger, heavier-gunned designs years before HMS Dreadnought.