text: After the end of the war, Olympia sailed to the Mediterranean via Portsmouth, England. In December 1918, the ship became the flagship for American naval forces stationed in the eastern Mediterranean Sea. While on this assignment, she continued in her old role of showing the flag and conducting goodwill visits in various Mediterranean ports. This included a period of policing duty in the Adriatic Sea from January 21 to October 25, 1919; the Dalmatian coast was in a state of turmoil following the collapse of the Austro-Hungarian Empire at the end of the war. On April 1, 1919, she was in Spalato, now Split, with  and . On August 18, she steamed to the Black Sea to aid the return of refugees from the Balkans who had fled during the war. She was back in the Adriatic Sea by September 19, and four days later had to deploy a landing party to prevent an incident between Italian and Yugoslavian forces.
  Olympia briefly returned to Charleston on November 24, 1919. The following year, she was reclassified CA-15. She then prepared for another tour of duty in the Adriatic, departing from New York on February 14, 1920. This was concluded on May 25, 1921, when the ship returned to Charleston. A month after her arrival she was made the flagship of the Atlantic Fleet's training unit. She then participated in joint Army-Navy experiments in July, during which the former German warships  and  were sunk off the Virginia Capes. She was again reclassified as CL-15 that year.