Empires love a beautiful administrative dream.
For early Tang rulers, one dream was especially elegant: a state where the same people who farmed the land could also defend it—a disciplined rotation of part-time soldiers who returned to their fields when the emergency passed. Not romance, not legend: a blueprint for turning war into something society “absorbs” through registration, land allotments, and obligation.
That dream is often summarized with one name: the fubing (府兵) system—militia soldiers who were expected to be self-supporting rather than full-time salaried troops. (Cambridge University Press & Assessment)
And like most administrative dreams, it didn’t collapse because people suddenly became lazy.
It collapsed because it worked too well—until the empire grew large enough that war stopped being an “exception”… and became a permanent condition.
1) If War Becomes a State of Being, Who Farms the Fields?
The soldier-farmer model assumes something quietly radical:
“The countryside can survive even when men leave.”
But expansion turns the border into a machine that never shuts off. Campaigns repeat. Garrisons become permanent. The state calls up the same bodies again and again.
Once rotation turns into extended absence, fields don’t politely wait. Households break. Local economies wobble. And the state’s most precious illusion begins to crack: the idea that its registries match reality.
In Tang military history, scholars often describe a shift from a system dominated by part-time militia to one relying more heavily on long-service recruits and permanent frontier forces—precisely because the strategic environment demanded troops who stayed, trained, and fought continuously. (Cambridge University Press & Assessment)
2) The Achilles’ Heel of Registration States: Running Away
Systems built on household registration and duty look strong—until you remember a brutal fact:
When the burden of service becomes ruinous, “obedience” stops being a moral category and becomes a survival calculation. Many premodern states discover the same nightmare: the moment citizens realize they’re safer as ghosts in the paperwork.
In Tang contexts, historians discuss policies aimed at re-registering missing households—a telltale sign that the state is no longer counting the same population it thinks it is counting. (Cambridge University Press & Assessment)
The state doesn’t just wage war.
At some point, it wages war against disappearance.
3) As Borders Expand, “Professional Soldiers” Are Not a Choice — They’re an Outcome
The fubing rhythm is cyclical: serve, return, farm.
But once the frontier stretches and rivals consolidate power, a border stop being a place you guard “for a while.” It becomes a place you live, with supply chains, families, markets, and routines.
That environment naturally produces a new type of soldier: career military men, increasingly recruited and maintained rather than rotated in and out. In Tang history, one major turning point often noted is the state’s move toward long-service recruitment; an edict in 737 is frequently cited in discussions of the growing prominence of such forces. (Cambridge University Press & Assessment)
And professionalization has a predictable price tag:
permanent pay and provisioning
larger logistics systems
more taxation and fiscal innovation
more administrators… and more power concentrated in fewer hands (Cambridge University Press & Assessment)
War ceases to be a social duty and becomes a budget.
4) From Frontier Garrisons to Mini-Governments: The Rise of the Jiedushi
Here’s the political twist that makes this story genuinely addictive:
When armies become permanent, command becomes local.
If a huge garrison is stationed far from the capital, it needs supply, discipline, law enforcement, and coordination. A commander who controls troops and logistics doesn’t stay “just” a commander for long—he becomes a regional power center.
By the early-to-mid 8th century, Tang frontier defense had coalesced into large regional commands, and many of these were led by jiedushi (節度使), military commissioners/governors with substantial authority. One overview notes that by 742 there were ten major frontier commands—nine headed by jiedushi. (Cambridge University Press & Assessment)
At that moment, the center’s language changes:
from orders to negotiations
from “administration” to “power-sharing”
from empire-as-machine to empire-as-network-of-strongmen (Cambridge University Press & Assessment)
The collapse of fubing looks like a military reform story—until you realize it’s actually a constitutional transformation in slow motion.
5) The Roman Parallel: The Death of the Citizen Army
Comparisons to Rome aren’t just flashy—they’re clarifying.
Both systems (in different ways) imagined armies rooted in ordinary households. Both encountered the same paradox:
Expansion requires longer wars.
Longer wars require professionals.
Professionals require money and command structures.
And command structures create political rivals. (Cambridge University Press & Assessment)
The route differs; the logic rhymes.
Once a military becomes a standalone institution, it is no longer merely a tool of the state. It becomes a player inside the state.
Conclusion: The Fall of Fubing Wasn’t “Decay.” It Was Imperial Growing Pains
The Tang soldier-farmer system didn’t collapse because people forgot virtue.
It collapsed because the empire traveled too far, fought too long, and demanded too much continuity from a model built for rotation. The shift toward permanent forces and powerful military governors wasn’t an accident; it was the empire’s own logic, played to its end. (Cambridge University Press & Assessment)
Seen this way, later explosions—like the kind of crisis symbolized by the An Lushan era—look less like random meteors and more like the final snap of a structure that had been creaking for decades. (Cambridge University Press & Assessment)
Modding Ideas: Turn This Into Addictive Game Mechanics
(1) Civilization-style design: This theme shines as Policies + Buildings (with a “too good early, risky late” arc)
A) Policy Card / Civic: “Fubing (Soldier-Farmer Integration)”
Pros (early game):
Farms gain +1 Production
Unit production +15%
Conscription cost reduced
Cons (scales with prolonged war):
If you stay at war for X turns: Growth −10% and Happiness/Loyalty penalty
Chance of a “Flight from the Registers” debuff (lower yields, higher unrest)
Core fun: it’s a power card that punishes you for staying imperial too long.
B) Building line: “Frontier Garrison (Junzhen)” → “Regional Command”
Bonus XP for stationed units + defensive strength
But upkeep increases
At a certain empire size or war duration, it evolves into…
C) Governor/City-State mechanic: “Jiedushi Authority”
Give frontier governors a special promotion:
Big military bonuses locally
But reduces central control, increases risk of separatist events
(2) Paradox-style design: This is an event chain waiting to happen
Event Chain: “Cracks in the Fubing System”
Triggers
Long war duration
Rising tax burden
Border garrisons become permanent
Peasant unrest threshold
Choices
Keep Fubing
Short-term savings
Long-term desertion/flight risk increases
Shift to Professional Army
Immediate cost spike
Stable military performance
But generals gain power (future coup risk)
Partial Reform (Re-registration Amnesty)
Temporary revenue boost
But strengthens local elites who “manage” the process
Endgame outcomes
Regional militarization (“Fanzhenization”)
Central authority erosion
A major rebellion crisis event (your custom “An Lushan-scale” shock)
The best part: the player doesn’t “get unlucky.”
The player chooses the seeds of the disaster.







