The first working submarine, the Nautilus, was constructed in Paris in 1801 by the American engineer Robert Fulton (1765−1815). Best known for his development, in 1807−8, of the first commercially successful steamboat, Fulton built the submarine, or “plunging boat,” in hopes that Napoleon would adopt it for use in his war with Great Britain. The French and later the British showed some initial enthusiasm for Fulton’s idea, but in the end both declined to support the project. Fulton then turned to steamboats as a way to finance his submarine research. The Library of Congress has in its collections a 71-page manuscript, signed by Fulton and dated August 10, 1806, entitled “On Submarine Navigation and Attack.” This document includes an introduction and detailed descriptions of 16 pen-and-wash drawings, also by Fulton, that accompany the text. Shown here is one of the drawings, which were numbered and signed by Fulton. Together, they touch upon almost every aspect of Fulton’s work in the fields of submarine and surface naval warfare. Fulton was born in Lancaster County, Pennsylvania. After working as a painter of miniature portraits and landscapes, in 1786 he went to London to study mechanical engineering. His other inventions include a machine for spinning flax, a dredging machine, and the torpedo.