Napoleon authorizes the Mesures usuelles

Background. In the five years immediately before the French First Republic introduced the metric system, every effort was made to make citizens aware of the upcoming changes and to prepare them for it. The system nonetheless remained unpopular in some circles. Napoleon, Emperor of the French since 1804, had implemented numerous legal and administrative reforms in France and Europe; the link between that reforming agenda and the measurement question is an editorial inference rather than a claim made in the sources.

The Imperial Decree. Under the décret impérial du 12 février 1812, Napoleon introduced the mesures usuelles, or customary measures, for use in small retail businesses. The system acted as a compromise between the metric system and traditional measurements, retaining familiar units rather than abolishing them in favor of the metric standard.

Context in 1812. The decree came during a demanding year for the Emperor: in late 1811 he had begun planning an invasion of Russia, launched in the summer of 1812, and a Franco-Prussian alliance signed in February 1812 bound Prussia to supply troops. The mesures usuelles formed part of his domestic administration alongside these military preparations.