In July 1921, Olympia joined a fleet of Navy spectator ships that witnessed General Billy Mitchell's revolutionary tests of aerial bombing against warships. Sitting a few miles from the test site, Olympia's crew watched the sinking of the captured German battleship Ostfriesland by U.S. Army aircraft. This successful demonstration proved the ability of aircraft to sink large ships. It foreshadowed the shift in naval orthodoxy from big guns to air power as the dominant form of naval warfare that would come to define World War II. Of all the ships that were present at this extraordinary and revolutionary event, only Olympia survives today.