Which French submarine, launched in 1904, was the first diesel-powered submarine?

The French submarine launched in 1904 that became the first launched submarine to use a diesel engine for surface running was French submarine Aigrette. Built for the French Navy, Aigrette was the lead boat of a small experimental class designed by naval engineer Maxime Laubeuf.

Aigrette was laid down at Toulon in 1902 and launched on 24 February 1904. Her diesel engine produced 150 horsepower for surface propulsion, while a 130-horsepower electric motor powered the boat underwater. This diesel-electric arrangement became the standard pattern for conventional submarines for much of the twentieth century.

The wording matters because Aigrette was not necessarily the first submarine ever ordered or commissioned with a diesel engine; historical accounts distinguish those milestones from the first one launched. She was commissioned in 1908 and served mainly in defensive and training roles. During the First World War she saw no combat, and she was sold for scrap in 1920. USS Holland and Germany’s U-1 were important early submarines, but they do not fit this specific 1904 milestone.