Why secondary guns could be the decisive weapons

Very large guns had political and visual value that exceeded their likely combat effect before reliable long-range fire control. They signalled battleship status to politicians and journalists, while ships still expected to fight at close range. Faster-firing 6-inch and smaller guns could kill exposed crews, batter mountings, and prevent an opponent's largest weapons from operating effectively. That vulnerability encouraged navies to protect heavy guns more completely and eventually return to turrets. Naval architects then had to solve the weight and machinery problem of rotating massive armoured structures at the ends of a ship.