First World War Under her original owners, the vessel saw service in the
First World War as a troopship. Little is known of her
Great War service, but it is fair to assume she was used mainly for trooping duties between the
Kent ports, Southampton and the main French port serving the
British Expeditionary Force at
Le Havre.
Viper was one of few transport ships which did not require the protection of an escort as her service speed was judged to provide her with enough protection.
Second World War At the outbreak of war, the Steam Packet operated a fleet comprising 16 ships. The
Rushen Castle and
Snaefell were kept to maintain the Isle of Man's vital link with the mainland,
Snaefell primarily as a relief vessel. For a while the joined them, and the , and stayed on to handle freight.
Snaefell was again
requisitioned and again used as a troopship, but after one year she was returned to the company and resumed her duty serving the Island's wartime link with the mainland, first to
Liverpool and then to
Fleetwood. ==Post-war service==