At exiting the school, he chose the field of Naval Engineering (Corps du génie maritime).

Bertin came to be known for his innovative designs, often at odds with conventional wisdom, and won international recognition as a leading naval architect.

For the French government, it represented a major coup in their fight against Great Britain and Germany for influence over the newly-industrializing Empire of Japan.

While in Japan, Bertin designed and constructed seven major warships and 22 torpedo boats, which formed the nucleus of the budding Imperial Japanese Navy.

These included the three Matsushima-class protected cruisers, which featured a single but immensely powerful 12.6-inch (320 mm) Canet main gun, which formed the core of the Japanese fleet during the First Sino-Japanese War of 1894–1895.

During the ceremony, the Navy Minister Saigo Tsugumichi (1843–1902) declared: Upon his return to France, Bertin was promoted to Director of the School of Naval Engineering (Ecole du Génie Maritime).

The Japanese were not happy with the overall performance of the Matsushima-class vessels, and after the cruiser Unebi sank en route from France to Japan in December 1886, Bertin's later designs were ordered from British, rather than French shipyards.