When, how and why did the Museum acquire this mask ?

No document provides an answer, but it is interesting to note that the Museum boasts a plaster cast of this same mask, and many other castings of skulls, busts and masks of key figures.
Part of these plaster castings comes from the Natural History Museum in Rouen, deposited in 1926, and the origin of the rest is unknown.
Napoleon’s bronze mask thus belongs to a 76-piece collection, held by the Museum and testifying to the development of casting techniques in the early 19th century, linked to the emergence of phrenology.