The Virtues Of Being Number One End At The Number Two.

There's a difference between "hegemon" and "unipolar super power." Athen's was the former (by virtue of the Delian League) before Sparta toppled it, Rome was the latter before it was toppled. In the last 60 years, the US has acted as both. You will, however, note the common verb in the two descriptions. [Hint: I'm not talking about "was."]