Modern historians seem to have a pretty good idea of how Roman legions functioned, from the individual kit of soldiers to recruitment to organization to military organization to tactics. Did lords or nobles in the Dark and Middle Age kingdoms that arose in the wake of the fall of the Roman empire - cognizant as they were of the Romans' success and power - ever attempt to replicate its military in order to replicate its success? Did they know enough details about the Roman military to be able to, or is that kind of detailed knowledge limited to modern historiography?