What practical use are guns that can fire farther than their spotters can see?
Short answerThey can engage fixed land targets and use external observers for corrections, though early signal-flag reporting was imperfect; modern forces face the same need for off-platform targeting.
NotesThe mismatch recurs across military technology: sometimes sensors outrun weapons, and sometimes weapons outrun the launching platform's organic sensors. Longer-ranged guns could still be useful against fixed land targets such as forts. Other observers might relay corrections by signal flag, although the attempted method was not an especially effective fire-control system. The same basic problem persists when modern weapons require targeting data from systems beyond their launch platform.