The eponym “Dejerine Sottas” makes 21st-century neurologists think of a form of heredity peripheral neuropathy leading to amyotrophy and secondary to a mutation of one of the many genes responsible for the formation of myelin. The seminal description was the work of Sottas and Jules Dejerine (1849–1917); Dejerine was the prestigious second successor of Jean-Martin Charcot at the Clinic of Nervous System Diseases at the La Salpêtrière hospital. Jules Sottas (1866–1945) has almost been forgotten, but as a young man he was a brilliant resident under Dejerine. However, Sottas eventually gave up medicine, even though he could have had a successful career as a neurologist, to devote himself to his passion for history, especially the history of navigation. But during his time as a physician he published several original works, always supported by detailed neuro-pathological studies, the result of his very close collaboration with Dejerine at Bicêtre then at La Salpêtrière. After a brief biography of Sottas, we will analyse his neurological work and then highlight the quality of his publications on naval and maritime history, which are still relevant today.