 She was built during the First World War as part of an emergency program of naval construction, to an Admiralty design by William Beardmore & Company, Dalmuir.She was originally to have been named "Magic" but she was renamed "Lassoo" on 15 February 1915 before being launched on 24 August 1915.She was sunk by the German U-boat SM "UB-10" on 13 August 1916 off the Maas lightship in the North Sea.