Complex sentence: Even when joined by a more contemporary fleet-mate in 1959, the "SS Rotterdam", the "Nieuw Amsterdam" still commanded a loyal following and remained one of the most popular ships on the north Atlantic.
Split into simpler sentences: Even when joined by a more contemporary fleet-mate in 1959, the "SS Rotterdam". The "Nieuw Amsterdam" still commanded a loyal following and remained one of the most popular ships on the north Atlantic.