Ocean liners as wartime troop transports

Were Titanic's contemporaries used as troop transports or otherwise employed in wartime?

Some were used, especially as fast troop transports, but their fuel demand and value made them expensive assets for wartime service.

Some large liners were used in war as troop transports or armed merchant cruisers, though their roles varied. Speed and capacity made them valuable for moving people quickly. Heavy fuel use and high financial value also made them assets commanders could not employ casually. Their wartime service turns the liner story into a logistics question as well as a history of commercial travel.