Pre-Modern Armies for Worldbuilders, Part I: Why They Fight
Points and comments are a snapshot, not live.
Military systems reflect their civilian societies: recruitment principles depend on whether service is entitlement, vocation, clientage, or employment.
Bret Devereaux begins a multi-part series on pre-modern army organization for worldbuilders. The central claim: armies recreate civilian hierarchies and structures on the battlefield, so understanding military systems requires first understanding the civilian society that produces them.
Devereaux outlines four foundational questions: Is the society agrarian? Is it a state? What kind of aristocracy does it have (military or warrior)? How do regular farmers relate to aristocrats (landowning, economically dependent, or administrative)? He then distinguishes four recruitment principles: the employment principle (pay for service), the entitlement principle (service as a requirement tied to citizenship rights), the vocational principle (standing armies or warrior aristocracies serving as their social role), and the clientage principle. He argues employment-based (professional) armies are rare in pre-modern societies and require strong bureaucracy and state revenues. The entitlement principle, by contrast, creates strong incentive to muster and remain because social identity and military obligation are tightly linked.
What commenters are saying
Commenters drew parallels to organizational dynamics. One noted Conway's law, suggesting human networks mirror across contexts (companies ship their org structure in products; armies do the same with civilian hierarchies). A lengthy subthread on Sparta and Rome dominated the discussion. Commenters agreed Sparta atrophied due to a closed, hereditary caste system based on purity, while Rome survived by expanding who could become "Roman," allowing ethnic incorporation and avoiding demographic collapse. One commenter clarified that wealthy citizens brought their own military equipment in systems like early Rome, making wealth a practical prerequisite for higher ranks; closed inheritance of status meant the ruling class shrank over time as infant mortality and military risk took their toll. Another noted the author's blog had already covered Sparta's actual history versus mythology.