Complex sentence: She was completed in November that year and entered service with the Dundee, Perth & London Shipping Company and sailed for them until the outbreak of the First World War, when she was requisitioned for use as an ocean boarding vessel.
Split into simpler sentences: She was completed in November that year and entered service with the Dundee, Perth & London Shipping Company. She sailed for them until the outbreak of the First World War, when she was requisitioned for use as an ocean boarding vessel.