How one 18-inch battleship could start an arms race

How should planners react if an otherwise equal opponent builds one battleship with 18-inch guns?

The immediate operational risk is manageable, but political pressure would probably trigger a costly 18-inch-gun arms race.

The tactical risk differs from the likely procurement reaction. One 18-inch-gunned battleship cannot be everywhere, may fire more slowly than 12-inch ships, and could be absent when the decisive battle occurs. Politicians, however, are unlikely to tolerate even a symbolic inferiority and would fund a matching ship. That response encourages the first navy to build another, turning one exceptional vessel into a new capital-ship standard.