 After fitting out, "Antares" joined the Fleet Train, replacing the old auxiliary .In March 1923, the ship became flagship for the Train, Scouting Fleet, a squadron of auxiliaries that supported those elements of the Fleet operating along the U.S. East Coast.Though her unit was later administratively incorporated into the Fleet Base Force as Squadron 1, "Antares" continued to wear the flag of the officer who commanded the auxiliaries on the Atlantic coast.