Military history of the Three Kingdoms

The military history of the Three Kingdoms period, part of the greater military history of China incorporated almost a century of prolonged warfare and disorder. Following the generally peaceful conditions of the Han Dynasty, the Three Kingdoms brought about changes unto military institutions and technology favouring the emergence of a professional hereditary soldiery, including an increasing reliance on non-Chinese cavalry forces and the closure of the Han system of universal conscription.

After the assassination of General-in-chief He Jin in September 189, the administrative structures of the Han government became increasingly irrelevant. The armies that fought the civil wars of the 190s were raised largely from voluntary recruits, though there was also some use of press-ganging as well as forcible enlistment of prisoners from defeated armies. Over the course of a decade the confusing mosaic of local violence resolved into a simpler pattern of regional conflict. By the death of Cao Cao, the most successful warlord of North China, in 220, the Han empire was divided between the three rival states of Cao Wei, Shu Han and Eastern Wu.

Wei
The military forces of the state of Wei originated in the personal army of Cao Cao. In late 189, he raised a force of some 5000 with his own resources and some donations. His earliest commanders and officers (Xiahou Dun, Xiahou Yuan, Cao Ren, Cao Hong, etc.) were all either his kinsmen or close relatives. After the downfall of Dong Zhuo, Cao Cao was able to establish a base of operations in Yan province (兗州). He was joined by a number of smaller, commonly clan-based, military entities. These included the personal forces of Li Dian, Xu Zhu, among others. In 192, Cao Cao also absorbed into his army some 300,000 former Yellow Turbans which he captured. These men maintained themselves as separate units known as the "Qing Province Army" (青州兵) until well after 220. In the multi-cornered wars of the 190s, all of these forces remained loyal for Cao Cao and later became the bulwark of the Wei armies.

Cao Cao was decisively defeated at the Battle of Red Cliffs in 208 and thereafter was never able to achieve significant gains against the marine forces of Sun Quan. Despite efforts by Wei at shipbuilding in 224 and again in 237, they had neither the technological expertise nor the human resources to break the defensive line of the Yangtze River.

Throughout the Three Kingdoms period, Wei always had the largest population and hence the most men in arms. Zhou Yu estimated that at Red Cliffs, Cao Cao could field 200,000 men. The size of the entire Wei military forces has been estimated at around 300,000. In 263, when the state of Shu was conquered, the build-up of Wei armies and the subsequent surrender of Shu troops may have swelled this number to half a million.

Cavalry and shock warfare
The conquest of the Wuhuan (207) and the northwest (211) allowed Cao Cao to effectively monopolise the employment of cavalry in China. The Wuhuan in particular had a reputation as the best cavalry force in all of China. Cao Cao also commanded the services of a considerable number of Xiongnu, and claimed that his army included contingents of Dingling, Di, Qiang, and several other northern nomadic peoples. Despite their relatively small numbers, mounted troops played a critical role and this was the trend not only during the Three Kingdoms but throughout the entire Chinese medieval period. It was around this time that the first mention of horse armour (馬鎧) can be found in the literary sources. Cao Cao boasted that with only ten sets of horse armour he had faced an opponent with three hundred. Although the use of stirrups, in combat at least, cannot be verified, representations of heavy cavalrymen of the Wei-Jin period appear to show them with their legs encased in heavy wooden sideboards to stabilize them on top of the horse. In north China at least, the natural mobility of cavalry, coupled with these innovations, gave it a considerable advantage over infantry.

Before battle, horsemen were needed for scouting and could be used for raids on the enemy's supply convoys; after the battle, they were essential for an effective pursuit. The main attraction of cavalry, however, was their capability for shock tactics, which was heightened by the volatility of the infantry. Their superior mobility enable them to maneuver to attack the flank or rear, or to quickly exploit any openings that might appear in the enemy line. Their height advantage made it easy for them to intimidate the opposing infantry, to throw them into panic-stricken flight with a sudden charge, or bull their way into and through the dense throngs of footsoldiers.

In combat, the horseback commander and his personal retainers acted as a spearhead for a drive through the ill-disciplined enemy array, akin to the methods used in northern Europe during the Dark Ages. Once battle had been joined, they tended to perform in a motivational rather than coordinating role by exposing themselves unto danger in the front ranks. These dangerous clashes of arms between individual leaders and their companions provided the basis of the countless epic duels of the Romance of the Three Kingdoms. Not unlike in the historical novel, success was often determined by the personal courage of commanders and their immediate followers.

Military institutions
Despite the conditions of the collapse of authority, there was actually a great deal of continuity in the Wei government. Hence the organisational structure of the Wei military was largely inherited from the Han administration. After the Battle of Guandu in 200, Cao Cao's army ceased to fight predominantly as a single entity with campaigns restricted to a few months. The absorption of the forces of Yuan Shao, Cao Cao's main rival in the north, led to a structural transformation in the military command. There emerged a highly professional "Central Army" (中軍) held in reserve, and various regional forces which came to be collectively called the "Outer Army" (外軍).

The role of the Central Army was not unlike that of the Northern Army (北軍) of Eastern Han, although it had a significantly more active role outside the capital. It originated from Cao Cao's personal guard, the so-called "Tiger and Leopard Cavalry" (虎豹騎). The earliest commanders of this elite unit were all Cao Cao's clansmen (Cao Xiu, Cao Zhen, Cao Chun). Its soldiers included Xu Chu, Dian Wei and their associated buqu (see "Buqu and hereditary armies" below). In 220, the Central Army had one regiment called "Zhongjian" (中堅), under the command of Xu Zhu. More were added by Cao Pi and Cao Rui so that by the 230s there were five regiments in all.

The Outer Army system was numerically many times larger than the Central Army, which probably never exceeded 50,000. In 222, Cao Pi subordinated the provincial units of the Outer Army to Chief Controllers (都督) appointed by the imperial court. These men were regular regional commanders who held responsibilities for military affairs within their frontiers. The regional armies they commanded are often also referred to as the "eastern army" (東軍). In addition to these forces, there were also territorial troops (州郡兵) raised by the Grand administrators (太守) or Inspectors (刺史). These men were distinguished by the fact that they could hold control of both civil and military affairs in their assigned regions. The potential problems of this system were recognised by contemporary politicians; a memorial was submitted by the eunuch official Du Shu (杜恕) calling for the abolition of military duties for Inspectors.

Buqu and hereditary armies
Buqu (部曲) were private fighting men for whom soldiering was a profession. Both bu and qu were regular units of military organization during the Han but by late Han and Three Kingdoms, the combination of the terms came to refer to the private retainer corps of armed men serving individual warlords in the capacity of personal dependents. The relationship between commander and buqu was in essence hereditary. When the commander died, a male member of his family would inherit control of his troops, and when a soldier died one of his male relatives would inherit his position in the rank. In essence generations of entire families became the agricultural servants and later the armed tenants.

Since Emperor Guangwu had disbanded the recruit (募兵) units in the first century AD, the provincial armed forces were purposely left weak and territorial armies were only raised in times of emergency. In a major break from the Han model, the government armies of Wei adopted a pattern of military service that was to a very large extent modelled after that of the buqu. The families of military men were concentrated in the capital and several other major centres, where they might serve as convenient 'hostages' while the soldiers were on campaign. This was largely due to the need to maintain a stable, reliable reservoir of manpower from which losses might be made good. The soldiers and their families were assigned a status as 'military households', subject to control by the military authorities. Soldiers and their relatives were only permitted to marry into other families with military status, to ensure that out-marriage would not lead over time to a diminution of the manpower pool, and of course they were expected to serve for life.

Unlike during the Han, ordinary commoners had no regular military service obligation, though in rare cases of urgent need men might still be conscripted for temporary duty.

Tuntian policies
The Tuntian policies were a system of military agriculture colonies established by Cao Cao for the purpose of supporting the military forces of Wei. Soldiers stationed in areas that were not at immediate risk of attack were ordered to cultivate farms.

Crossbows
Although crossbows had been in use for hundreds of years before this time, its design and model during this era is unknown. The crossbow used during this time period is more likely used in large group of marksmen deployed to fire waves of bolts (crossbow ammunition) onto enemies from afar. The crossbow itself has superior range than normal bows. Thus it becomes more commonly used like an artillery purpose than sniping. Crossbows has been in use in China since the Zhou dynasty over 700 year earlier (approx. 500 BCE).

In the later years, the great strategist and inventor Zhuge Liang had devised a more complicated platform. A multiple bolt firing crossbow and a semi-automatic crossbow (which some sources call Chu'ko'nu, literally 'Zhuge Crossbow') was created to be used as an anti-personnel weapon.

Riverine warfare
In the south, the Yangzi River provided the great military highway that both facilitated and channelled military operations. The area around Hefei was under constant pressure from Wei, and warfare grew so intense that many of the residents chose to migrate en masse and re-settle south the Yangtze. Yet Wei never succeeded in breaking through the line of river defences erected by Wu, including the formidable Ruxu forts. Southern mastery of the tools and techniques of riverine warfare conferred a huge defensive advantage. The drier north produced fewer individuals with the necessary skills for riverine warfare.

In contrast to ramming and boarding techniques seen in Europe, the most common tactics involved the use of missiles to damage enemy vessels and kill or injure members of their crews and this remained the norm until colonial times. The heavy emphasis on missile combat tended to favour defence over offence in naval actions and made it rather difficult to eliminate sturdily built enemy ships. The major exception with this general rule was an attack with fireships, which was demonstrated with decisive effect at the Battle of Red Cliffs.

Various classes of vessels are known of under names such as "Flying Cloud" and "Green Dragon Warship", and according to Pei Songzhi's annotations, a ship carrying 80 horses was considered to be small. Certainly, Wu shipbuilding had progressed onto an advanced level, as evidenced by the expedition of 10,000 warriors to Sichuan (then called Yizhou) in 230. It is also known that these ships existed on a large scale. When Wu was finally conquered by Jin in 280, some 50,000 vessels - some of which were for transport - were seized. The ultimate Jin victory owed much unto the fact that Wang Jun's fleet was more powerful than the southern water forces, and that he was able to outflank Wu from the west. As long as Wu held control of the waterways, no army from the north could succeed in conquering Wu.