N-6 was launched on 21 April 1917 sponsored by Mrs. John A. Kissick, and commissioned on 9 July 1918 with Lieutenant Commander Herbert R. Hein in command.
Service history
After outfitting at New London, Connecticut, she commenced patrolling off the New England coast to protect coastal shipping from German U-boats. She alternated operating out of New London and New York City until she put into the former port on 13 October for upkeep. With the exception of a training cruise up the New England coast from 14 to 19 July 1919, and a voyage to New York Navy Yard from 29 September to 9 October, N-6 remained at New London until sailing in early May 1920 for Annapolis, Maryland, arriving on 27 May. There, she was used to indoctrinate midshipmen of the United States Naval Academy in submarine warfare.