Complex sentence: The Italian Line had lost most of their passenger liners during World War II, including the prestigious SS "Rex" and SS "Conte di Savoia", with all of the ships that did survive the war dating from the 1920s.
Split into simpler sentences: The Italian Line lost most of its passenger liners during World War II, including the prestigious SS "Rex" and SS "Conte di Savoia". All of the ships that did survive the war dated from the 1920s.