During the First French Republic, in what we now know as the Provinces of Namur and Luxembourg, Belgium, was then part of the department of Sambre-et-Meuse of France. Today, that department no longer exists.

You can find early Belgian military enlistments from as early as 1796 to as late as 1890 in the Hainaut province. Not all towns carry these military inscricts enlistment records, but a lot of towns do. Check here for all of the towns in the Province of Hainaut that house these military records. Keep in mind that each municipality has their own set of years available.
Municipalities in the Provinces of Luxembourg and Namur, provide certificates on completion of the soldier’s military service. You can find this military extrait sandwiched in between marriage records of the adult male at age 20 or above. This military record contains most of the information you would find in the indexed recruitment record.
Updated! Memoire des Hommes; Military Enlistments of the ‘L’Ancien Régime 1682-1793 Military Enlistments and Campangies of the Ancient Regime. Also includes men from what is now known as Belgium. This is a MASSIVE browsable depository of all recorded enlistments with images, of different branches of army i.e. Infantry, Calvary, Artillery and more. It covers the names of soldiers, towns of Enlistments and battlefields. Early records have regions and Provinces (ex: Anjou) that might not exist today. Unfortunately, this is not a searchable repository, only a browsable one. There are filters on the right side of the page that help narrow down fields so you can browse better. Click here for instructions on how to navigate through this database..
Updated! Mémoire des Hommes
Database of community indexed military enlistments of soldiers born in Belgium. Another search of Belgium through the ‘Pays de naissance‘ includes those men who were born in jurisdictions or regions, or in parts of other countries that is now part of Belgium. The records can begin as early as 1719 to the end of the Napoleonic era. You can search by names or by other department of naissance’ or ‘pays de naissance’. This is an incomplete but growing indexing project. With images
Find Belgium Military Records of the Province of Hainaut-
An easy way to find Belgium’s nineteenth century and even late 1790s military & enlistment records of towns that provide those documents here The available records are published and found by Family Search. Or you can do old school style by navigating FamilySearch to the country of Belgium, and then to the province and pick from each town find the ones that do have those military records. I do have a tutorial for that, you can find additional categories of records for that town and province.
The War Dead Register–
A searchable database of First and Second World War’s Belgian casualties
In Flanders Field-1914-1918
A searchable list of soldiers’ names of Belgians who died in WWI- This is an on-going project