In the period 1802-1815 the (in)famous Emperor Napoleon Bonaparte was at war with the other European powers. The recruitment of men required for his huge army - volunteers and conscripts - was enormous, likely the largest in France - except for the First World War.
Initially, a series of military victories allowed the French Empire to exercise unprecedented control over most of Europe. During the disastrous invasion of Russia in 1812, however, Napoleon's army suffered enormous losses, after which it never recovered its tactical superiority.
Unlike most armed forces at the time, Napoleon's army operated on a strictly meritocratic basis; while most contingents were commanded by French generals - except for the Polish and Austrian corps, most soldiers could climb the ranks regardless of class, wealth, or national origin.
Over 1 million soldiers have now been indexed from their military roll register records, while indexing of the remainder is ongoing. Each record contains the family name, first name, date and place of birth, parents' names, enrollment and discharge dates, and campaign records for every soldier. A link to the high-resolution scanned image hosted by France's Ministère des Armées is added, too. Most records are for French soldiers, but there are also men from other European countries like Belgium, Germany, The Netherlands, Italy, and Poland.
One of those many soldiers in Napoleon's “Grande Armée” was my ancestor Arie de Sterke (1796-1892).
You can search here at GeneaNet.org :
https://en.geneanet.org/fonds/search-event/76/napoleon-s-soldiers
Note: When searching, keep in mind that a French version of the given name may have been written down, for example "Jacques" i.s.o. Jacob(us).
Further reading: Wikipedia.org