At the time of the Industrial Revolution, the fact that each state had its own system of weights and measures became increasingly problematic. Serious work on a "scientific" system was started in France under Louis XVI, and completed in 1799 (after the French Revolution) with its implementation. The French population, however, was initially unhappy with the new system. In 1812, Napoleon Bonaparte reintroduced some of the old measurements, but in a modified form that was defined with respect to the metric system. This  was finally abolished in 1837 and became illegal in 1840.
Due to the large expansion of the First French Empire under Napoleon I, French metrication also affected what would be (parts of) France's neighbour countries after the Congress of Vienna.
The Netherlands were partially metricated when they were French, in the years 1810–1813. With full metrication, effective January 1821, the Netherlands reformed the . The apothecaries new pound was 375.00 g. Apart from rounding issues concerning the subdivisions, this corresponded exactly to the French . (The reform was not followed in the north German city of Lübeck, which continued to use the .) In Belgium, apothecaries weight was metricated effective 1856.
From 1803 to 1815, all German regions west of the River Rhine were French, organised in the  Roer, Sarre, Rhin-et-Moselle, and Mont-Tonnerre. As a result of the Congress of Vienna these became part of various German states. A large part of the Palatinate fell to Bavaria, but having the metric system it was excepted from the Bavarian reform of weights and measures.