In essence, the Carolingian army was an odd sort of layer-cake, in part because it represented a transitional stage from the Germanic tribal levies of the earliest Middle Ages towards to emergence and dominance of the mounted aristocracy of the early part of the High Middle Ages (note: the Middle Ages is a long period, Europe is a big place, and it moves through a lot of military systems; to talk of a single “medieval European system” is almost always a dangerous over-generalization). The top of the layer-cake consisted of the mounted aristocrats, in basically the same organization as the lords of Rohan discussed above: the great magnates (including the king) maintained retinues of mounted warriors, while smaller (but still significant) landholders might fight as individual cavalrymen, being grouped into the retinues of the great magnates tactically, even if they weren’t subordinate to those magnates politically (although they were often both). These two groups – the mounted magnate with his retinue and the individual mounted warrior – would eventually become the nobility and the knightly class, but in the Carolingian period these social positions were not so clearly formed or rigid yet. We ought to understand that to speak of a Carolingian “knight” (translated for Latin miles, which ironically in classical Latin is more typically used of infantrymen) is not the same, in social consequence, as speaking of a 13th century knight (who might also be described as a miles in the Latin sources).

But below that in the Carolingian system, you have the select levy, relatively undistinguished (read: not noble, but often reasonably well-to-do) men recruited from the smaller farmers and townsfolk. This system itself seems to have derived from an earlier social understanding that all free men (or all free property owning men) held an obligation for military service; Halsall notes in the eighth century the term arimannus (Med. Lat.: army-man) or exercitalis (same meaning) as a term used to denote the class of free landowners on whom the obligation of military service fell in Lombard and later Frankish Northern Italy (the Roman Republic of some ten centuries prior had the same concept, the term for it was assidui). This was, on the continent at least, a part of the system that was in decline by the time of Charlemagne and especially after as the mounted retinues of the great magnates became progressively more important.

We get an interesting picture of this system in Charlemagne’s efforts in the first decades of the 800s to standardize it. Under Charlemagne’s system, productive land was assessed in units of value called mansi and (to simplify a complicated system) every four mansi ought to furnish one soldier for the army (the law makes provisions for holders of even half a mansus, to give a sense of how large a unit it was – evidently some families lived on fractions of a mansus). Families with smaller holdings than four mansi – which must have been most of them – were brigaded together to create a group large enough to be able to equip and furnish one man for the army. These fellows were expected to equip themselves quite well – shield, spear, sword, a helmet and some armor – but not to bring a horse. We should probably also imagine that villages and towns choosing who to send were likely to try to send young men in good shape for the purpose (or at least they were supposed to). Thus this was a draw-up of some fairly high quality infantry with good equipment. That gives it its modern-usage name, the select levy, because it was selected out of the larger free populace.

And I should note what makes these fellows different from the infantry who might often be found in the retinues of later medieval aristocrats is just that – these fellows don’t seem to have been in the retinues of the Carolingian aristocracy. Or at least, Charlemagne doesn’t seem to have imagined them as such. While he expected his local aristocrats to organize this process, he also sent out his royal officials, the missi to oversee the process. This worked poorly, as it turned out – the system never quite ran right (in part, it seems, because no one could decide who was in charge of it, the missi or the local aristocrats) and the decades that followed would see Carolingian and post-Carolingian rulers more and more dependent on their lords and their retinues, while putting fewer and fewer resources into any kind of levy. But Charlemagne’s last-gaps effort is interesting for our purpose because it illustrates how the system was supposed to run, and thus how it might have run (in a very general sense) in the more distant past. In particular, he seems to have imagined the select levy as a force belonging to the king, to be administered by royal officials (as the nation-in-arms infantry armies of the centuries before had been), rather than as an infantry force splintered into various retinues. In practice, the fragmentation of Charlemagne’s empire under his heirs was fatal for any hopes of a centralized army, infantry or otherwise, and probably hastened the demise of the system.

Beneath the select levy there was also the expectation that, should danger reach a given region, all free men would be called upon to defend the local redoubts and fortified settlements. This group is sometimes called the general levy. As you might imagine, the general levy would be of lower average quality and cohesion. It might include the very young and very old – folks who ought not to be picked out for the select levy for that reason – and have a much lower standard of equipment. After all, unlike select levymen, who were being equipped at the expense, potentially, of many households, general levymen were individual farmers, grabbing whatever they could. In practice, the general levy might be expected to defend walls and little else – it was not a field force, but an emergency local defense militia, which might either enhance the select levy (and the retinues of the magnates) or at least hold out until that field army could arrive.

Bret Devereaux, “Collections: The Battle oF Helm’s Deep, Part IV: Men of Rohan”, A Collection of Unmitigated Pedantry, 2020-05-22.