Adriatic reopened White Star Line’s Southampton-Cherbourg-New York service on 3 September 1919 accompanied by the
Lapland, to ensure provisional service pending the return of requisitioned ships and the arrival of new liners.
In December, the
Lapland was returned to Red Star Line service. From January through June 1920,
Adriatic maintained the Southampton service on her own until
Olympic returned to service after her post war refit on 25 June 1920.
Throughout 1920,
Olympic and
Adriatic made a combined 37 crossings and carried a combined 59,660 passengers for an average of 1,612 passengers per crossing.
Olympic carried 28,458 passengers over 16 crossings for an average of 1,779 passengers per crossing and
Adriatic carried a career high 31,202 passengers over 21 crossings for an average of 1,486 passengers per crossing.
Adriatic was finally withdrawn from the Southampton route after a last crossing, on 14 December 1921, in view of the arrival of the
Majestic and the
Homeric. After a Mediterranean cruise in January 1922 and a subsequent overhaul in Belfast, she rejoined her sisters on the Liverpool route on 13 May 1922.