The Historical Context of Jin’s Military Reforms

During the turbulent early Spring and Autumn period (770-476 BCE), the state of Jin emerged as one of the most powerful warring states in ancient China. The military landscape of this era was dominated by chariot warfare, where aristocratic warriors fought from horse-drawn chariots supported by conscripted infantry. However, as warfare intensified and border threats grew, Jin found itself needing to adapt its military structure to meet new challenges.

The critical turning point came in 632 BCE when Duke Wen of Jin, one of the famous “Five Hegemons” of the Spring and Autumn period, established three specialized infantry units known as the “Three Divisions” (三行). This revolutionary military reform marked the first time in Chinese history that infantry was organized as independent combat units rather than merely as support for chariot forces.

The Creation and Structure of the Three Divisions

Duke Wen’s Three Divisions were organized with clear military hierarchy and specialization:

– Central Division (中行): Commanded by Xun Linfu
– Right Division (右行): Led by Tu Ji
– Left Division (左行): Under the command of Xian Mie

Unlike the traditional Three Armies (三军) that formed the core of Jin’s military, the Three Divisions had a simplified command structure with only generals and no deputy commanders. This organizational difference reflected both their lower status compared to the chariot forces and their smaller troop numbers.

The creation of these specialized infantry units represented a significant elevation in the status of foot soldiers. Historical records suggest these divisions performed admirably in battles against Qi at An (鞌之战), where infantry of Rong origin successfully repelled Qi’s final assault. The term “出身行伍” (coming from the ranks), which later became a common expression for military service, originated from these Three Divisions.

Strategic Purpose and Hidden Agenda

While officially created to defend against nomadic Rong and Di tribes along Jin’s borders, the Three Divisions likely served a more strategic purpose. Duke Wen merged them with the Three Armies just two years after their creation to form a new Five Army system. This rapid reorganization suggests the infantry divisions were never intended as permanent frontier defense forces but rather as:

1. A covert military expansion to circumvent Zhou dynasty restrictions on army sizes (only the Zhou king could maintain six armies, while major states were limited to three)
2. A reserve force that could be quickly mobilized and equipped with chariots when needed
3. A political tool to strengthen the duke’s power against powerful aristocratic families

This strategy bears striking resemblance to military workarounds used by Germany after World War I and the Soviet Union before World War II, where nations maintained skeleton units that could be rapidly expanded during mobilization.

Evolution of Chariot-Attached Infantry

The development of the Three Divisions occurred alongside significant changes in chariot warfare organization. From early Western Zhou to mid-Spring and Autumn period, the number of infantry attached to each chariot grew dramatically:

– Early Zhou: 27 infantry per chariot (7 armored warriors + 20 conscripts)
– Mid-Spring and Autumn: 75 combat troops + 25 support personnel per chariot

This expansion was made possible by military reforms that:
– Blurred distinctions between urban (国) and rural (野) populations for conscription
– Allowed wealthy commoners to serve as armored infantry
– Reduced the requirement for aristocratic warriors per chariot from 10 to just 3

Cultural and Social Impacts

The military reforms reflected and accelerated broader societal changes:

1. Social Mobility: Commoners gained military importance, challenging aristocratic dominance
2. Economic Reforms: Land ownership changes (“作爰田”) increased agricultural productivity and military manpower
3. State Centralization: The duke strengthened control over regional aristocrats
4. Cultural Integration: Incorporation of Rong and Di tribes into Jin’s military fostered ethnic mixing

However, these reforms also planted seeds for Jin’s eventual division, as empowered aristocratic families like Zhao, Wei, and Han grew too strong for the ducal house to control.

Military Legacy and Historical Significance

Though short-lived as independent units, the Three Divisions established important precedents:

1. Demonstrated infantry’s potential as an independent combat arm
2. Pioneered military organizational reforms that would culminate in the Warring States period
3. Influenced later infantry tactics and formations
4. Marked the beginning of infantry’s rise to dominance in Chinese warfare

The reforms also reflected broader trends in Spring and Autumn period warfare:
– Increasing army sizes and battlefield complexity
– Growing importance of combined arms tactics
– Professionalization of military forces
– Adaptation to new threats and technologies

Conclusion: The Dawn of a New Military Era

Jin’s Three Divisions represented a crucial transitional phase in Chinese military history. While chariots would remain important for centuries, the elevation of infantry status marked the beginning of a fundamental shift in warfare. These reforms demonstrated how military necessity could drive social and political change, as states adapted traditional systems to meet new challenges.

The story of the Three Divisions offers valuable insights into how ancient states balanced tradition with innovation, and how military reforms could both strengthen a state in the short term while creating new challenges for the future. Their legacy would influence Chinese warfare throughout the turbulent Warring States period that followed.