Fantastic collection of 236 volumes of military prints available for free download from the Bibliotheque Nationale de France here.

Collections are mainly European and range from C17-C19th with a focus on French troops (lots of Nap I and Nap III). I've downloaded all the Nap I ones I can spot (you have to hunt through the listings), as below.


Some examples:
https://gallica.bnf.fr/ark:/12148/btv1b8426859v/f1.planchecontact.planchecontact

https://gallica.bnf.fr/ark:/12148/btv1b8427292q/f31.planchecontact

https://gallica.bnf.fr/ark:/12148/btv1b10020316h/f11.planchecontact

https://gallica.bnf.fr/ark:/12148/btv1b84268504/f1.planchecontact.planchecontact

https://gallica.bnf.fr/ark:/12148/btv1b84272897/f1.planchecontact.planchecontact

https://gallica.bnf.fr/ark:/12148/btv1b8426830c/f6.planchecontact

The BnF also has collections of art prints, books, ref works etc, all available online.