[Lee Sang-hoon's Korean History] Silla's Secret Weapon was the 印章... It Granted 'Power' and Demanded 'Sacrifice'

Strategy That Led to Victory in the Nandang War

Professor Sang-Hoon Lee, Korea Military Academy

Why did Silla distribute seals (印章) during wartime?

In January 675, Silla distributed copper seals (印章) to various government offices (百司) and local jurisdictions (州郡). This was just before the height of the Silla-Tang War, which had intensified since 670. The war ended with Silla's victories at the Battle of Maesoseong in September 675 and the Battle of Gibeolpo in November 676. Why did Silla distribute copper seals nationwide in 675, seemingly unrelated to the war?

In East Asia, characters were inscribed on oracle bones (甲骨) or bronze artifacts. However, due to limited availability of materials and the difficulty of engraving, these were mainly used by elites or for ritual purposes. Later, wood replaced these materials. The use of easily accessible wooden tablets, called mokgan (木簡), led to an explosive increase in knowledge and information recording. This is considered a background factor for the emergence of various philosophical schools during China's Spring and Autumn and Warring States periods.

In the pre-modern era, the basic elements for maintaining a state were economic power and military strength. State policies were documented according to laws and regulations. Document administration inevitably developed to collect taxes and conscript labor. However, enforcing laws and mobilizing personnel through documents carried risks, as documents could be altered or forged during transmission to lower levels. Therefore, ensuring the reliability of documents was necessary.

Before the widespread use of paper, wooden tablets were used for document administration. Maintaining the security of mokgan documents was crucial. A wooden strip called geom (檢) was added and attached to the mokgan. After applying clay to seal it, a seal was stamped on the clay, called bongni (封泥).

For dispatching mokgan, the geom was attached and tied with a string to secure it. Then, a bongni seal was stamped on top, and the document recipient's office (署) was written. If the bongni seal attached to the geom was broken, it was considered that someone had exposed the document through abnormal means.

If the geom and bongni remained intact, it was basically impossible to modify or manipulate the document content during transmission. In Korea, mokgan were mainly excavated from Nakrang (樂浪) sites around Pyongyang, dating to the Han dynasty period. Many mokgan and bongni were found, with bongni being fragments that fell off when sealed mokgan were opened. Mokgan, widely used in ancient times, disappeared with the advent of paper.

At the height of the Silla-Tang War,
copper seals distributed to Silla's government offices and local jurisdictions.
Not the usual soapstone but copper seals distributed,
establishing a hierarchy.
Part of the central-local administrative system.

Most commanders at the fierce Battle of Maesoseong
were local officials.
Some authority delegated via seals.
Boosted morale before the decisive battle.
No records of central army support.

Generally, paper is known to have been invented during the Former Han dynasty in China and improved by Cai Lun (蔡倫, ??121) during the Later Han dynasty. Early paper was made from hemp fibers, called maji (麻紙). The invention of lightweight and convenient paper was revolutionary. The volume of document production surged, and transmission speed greatly increased. Paper quickly replaced the heavy and inconvenient mokgan.

After the Han dynasty, paper became widely distributed in China, bringing significant changes to document administration. The bulky and cumbersome geom gradually disappeared. Consequently, the need for bongni also vanished. Instead of geom and bongni, seals and signatures (署名) became important. Seals evolved from intaglio (陰刻) in the bongni era to relief carving (陽刻) in the paper era, and were stamped directly on paper with red ink (印朱). Signatures indicating the document creator evolved uniquely to prevent forgery.

Ancient Chinese seals were broadly divided into official seals (官印) and private seals (私印). Official seals were further classified into government office seals (官府印) and official name seals (官名印). Seal shapes were diverse without fixed forms, and materials varied widely. The most commonly used material was copper (銅), followed by jade (玉). Other materials included silver, glass, bone, and clay.

The seal face (印面) was most commonly square, followed by rectangular. Other shapes included circular, curved, triangular, and rhombus. A hole called nyu (?) was made at the top of the seal, through which a string could be threaded to wear it on the waist.

In Korea, the Dangun myth records a "Cheonbuin (天符印)" seal. The Samguk Sagi records that in the 16th year of King Namhae of Silla (AD 19), a person from Bukmyeong (北溟) found and presented the "Yeowangjiin (濊王之印)" while working in a field. Also, in the first year of King Sindae of Goguryeo (165 AD), after the assassination of King Chadae, the left assistant (左輔) Eojiryu (?), presented the "Guksae (國璽)" to the king's younger brother.

Wooden seals (mok-in, 木印) were also discovered at Anapji in Gyeongju, the capital of Silla. Various seal records including Cheonbuin have been confirmed, indicating that seals became widespread by the Three Kingdoms period regardless of their exact nature.

During the height of the Silla-Tang War, Silla distributed copper seals to various government offices and local jurisdictions. It is unlikely that official seals were first created in Silla in 675 during King Munmu's 15th year, as Chinese-style seals were already present in the Jinhan society in the early 3rd century. Therefore, it is highly probable that seals were already in use in government offices before the 675 distribution of copper seals.

Document administration refers to handling state affairs through documents according to laws. Ancient administrative documents were not arbitrarily created by officials but produced, discarded, and preserved according to laws, with these processes regularly inspected and controlled. The management of seals, which indicated final confirmation and approval in document administration, would have followed the same principles.

At Daemosanseong Fortress in Yangju, Gyeonggi Province, both soapstone and bronze seals were excavated. Soapstone, also called talc or steatite, is soft and slippery. Soapstone seals were generally used for routine work. Bronze seals were considered high-grade seals used for prestigious documents. By distributing copper seals to local offices, Silla appears to have established a hierarchy between high-grade and routine seals, reflecting the systematization of central and local administration.

"In emergencies, requests must be made in writing; oral or proxy requests are prohibited." This phrase was recorded on bamboo slips (죽간, 竹簡) excavated from a Qin dynasty tomb in Yunmeng County, Hubei Province, China. It clearly shows the importance of document administration. Especially in military affairs, document administration must be handled swiftly and accurately.

The timing of Silla's distribution of copper seals in 675 was just before the decisive battle with Tang. In this context, the distribution of seals likely had another meaning. In wartime, awarding seals could boost the morale of each agency head and officially delegate some of the king's authority. This was a measure to guarantee a certain degree of autonomy to agency heads in the wartime system, enabling faster and more efficient responses to rapidly changing situations.

In August 672, commanders at the Battle of Seokmun were mainly generals from the noble bone (진골) class. However, at the decisive Battle of Maesoseong in September 675, most commanders were local officials such as seongju (城主), hyeollyeong (縣令), and sosu (少守). Moreover, there are no records of reinforcements from the central Silla army during the fall of the fortress. Since all deceased commanders were local officials, it seems Silla deliberately withheld support for local fortresses.

From the perspective of individual local fortresses, the actions of Silla's leadership might seem cruel. However, considering the overall situation of the Silla-Tang War, it was a desirable choice. The Tang army had to attack hundreds of Silla fortresses one by one while advancing south. They also had to leave some troops to defend the captured fortresses.

The farther the Tang army advanced south, the longer their supply lines became, and their attacking forces gradually diminished. Silla understood this situation and engaged in a war of attrition. They avoided large-scale frontal battles and opted for a war of attrition, causing logistical problems for the Tang army. Ultimately, Silla's defensive strategy was effective. After the Battle of Maesoseong in 675, the Tang army had no choice but to withdraw from the Korean Peninsula.

Professor Sang-Hoon Lee, Department of Military History, Korea Military Academy