The Wokou in Goryeo-Joseon Korea

Pirates in the Goryeo Annals

The wokou phenomenon evolved significantly over time, beginning as a series of sporadic maritime raids before transforming into a more organized and devastating force by the 14th and 15th centuries. According to Korean and Japanese chronicles across the Goryeo and Joseon dynasties, the pirates said to be hailing from the islands nearest to Korea – Iki and Tsushima – began raiding the Korean peninsula in the second quarter of the 13th century. M.S Seoh notes that the first record of the Korean term “Waegu,” was in the Goryeo-sa, the historical record of the Goryeo dynasty. It is said in 1223, during the reign of King Gojong (1213-1259), Japanese Waegu invaded Kimju.

As the wokou in this time period were understood to be Japanese, we would be focusing on how the wokou have shaped the diplomatic communications between Korea and Japan, across both the Goryeo and Joseon dynasties. Goryeo’s growing urgency for assistance reflected how wokou attacks began to escalate in intensity and frequency. To be able to examine this escalation, we would be chronologically analysing these interactions. One of the earliest examples of such engagement can be found in the annal entry on May 1227, where in response, the Japanese court sent a letter to Goryeo apologizing for the actions of pirates and proposed the establishment of peaceful relations and trade.

Japan invades Kimju. Goryeo-sa entry on May 22, 1223, during the reign of King Gojong (1213-1259). Image and descriptions courtesy of Database of Korean History: Goryeo Era. Accessed April 15, 2025. https://db.history.go.kr/goryeo/

Japanese response to Wokou raids in Korea. Goryeo-sa entry on May 17, 1227, during the reign of King Gojong (1213-1259). Image and descriptions courtesy of National Institute of Korean History, Database of Korean History: Goryeo Era. Accessed April 15, 2025. https://db.history.go.kr/goryeo/

Goryeo-Bakufu Relations

Diplomatic relations between Japan and Korea prior to the wokou era were already fraught with tension. Although some trade and religious exchanges occurred, political relations remained minimal because Korea, operating within Imperial China’s “inequality” diplomatic framework, sought equal standing with Japan. A 1226 entry in the Meigetsuki, a court diary written by a Japanese noble, captures the tension and uncertainty surrounding Korea-Japan relations during the early 13th century. The entry reads:

"On the 16th. Clear weather. In a message from the monk Hōgen, it was said that the country of Tsushima had a dispute with Goryeo. There are rumors circulating in the streets, but it is uncertain whether they are true. Due to the dire state of the world in these final days, could it be that an enemy nation is coming to attack? It is frightening and sorrowful."

Times of Tension

This entry highlights the anxieties and perception of Goryeo among Japanese elites. Even a rumor of a dispute with Tsushima had sparked fears of foreign invasion. Such sentiments underscored a broader climate of uncertainty in the region, and these sentiments were not unfounded. It is written in the Azuma Kagami Tatsuro, a shogunate chronicle, that on May 14, 1227, a formal letter from the Goryeo Inspector of Jeolla Province arrived at the Dazaifu government in Kyushu, providing a detailed complaint against the people of Tsushima Island. The letter revealed the depth of the brewing crisis:

"From ancient times, people of Tsushima Island in your country have offered tribute to ours, and each year we have maintained friendly relations. In accordance with your country’s convenience, we have specially provided official lodgings and treated your people with kindness and trust... However, according to the report from Jin-hae Prefecture, Tsushima people, relying on their old residence there, one night in the sixth month of the Byeongsu year (1226), entered through a hole in the city walls while our people were asleep, and looted the main residences. This has gone beyond all acceptable limits… Innocent commoners are repeatedly harassed… Additionally, the originally established tribute system and formal exchanges have ceased entirely. There are now many vessels sailing without regulation, with irregular comings and goings, committing wicked deeds…"

Both an indictment and a plea,

The letter accuses the Japanese authorities of failing to manage their own island subjects, whose interactions had turned violent. The message conveys a sense of betrayal—despite historical ties and hospitality extended to Tsushima emissaries, Goryeo now faced raids and plundering, an alarming breach to their diplomatic relations. The reference to “many vessels sailing without regulation” points directly to the absence of official maritime order, a precursor for the chaotic conditions that would later give rise to the wokou pirates. Japan’s inability, or perhaps unwillingness to control its subjects along its maritime peripheries, especially in Tsushima, created a space for lawlessness that directly undermined interstate relations. In turn, Goryeo’s appeals to order and justice were met with silence or insufficient response, allowing distrust and resentment to fester. These early fractures in Korea-Japan relations laid the groundwork for the violent escalations of the later Wokou period. It is also important to note that the fragmented authority within Japan’s feudal structure also undermined any solid effort to prevent or respond to piracy. A 1232 entry from the Azuma Kagami, details the Shugo’s (military governor) investigation of a suspected pirate who crossed over to Goryeo intending to carry out a night raid. The entry as follows:

"He stole a large amount of treasure and, on his return to Japan, the local Shugo tried to question him in detail about the matter and intended to summon the culprits involved. However, previously it had been stated that this matter was not under the jurisdiction of the Shugo. Therefore, a directive was submitted in advance on this point. Today, a ruling was made: since this is not a matter that should be suppressed, the names of those involved shall be handed over immediately, and they are to be summoned to the Shugo’s office. The ship and the stolen goods are also to be handled together in accordance with legal procedure."

Products confiscated from the Japanese Wokou. Goryeo-sa entry on August 1, 1263, during the reign of King Wonjong (1260-1269). Image and descriptions courtesy of National Institute of Korean History, Database of Korean History: Goryeo Era. Accessed April 15, 2025. https://db.history.go.kr/goryeo/.

Curbing the Wokou

While the local Shugo attempted to intervene and summon the culprits, he was initially blocked from doing so on the grounds that the matter was outside his jurisdiction. Legal action could only be made after an official directive was issued, and the culprits were ordered to be handed over, along with their ship and stolen goods. Despite occasional gestures toward accountability, as evidenced in this case, such enforcement remained inconsistent and largely ineffective.

Even the Bakufu’s attempts to curb piracy saw only a temporary drop in raids, with the pirates simply relocating their bases beyond Japanese jurisdiction. Later on in 1381, an order from the Muromachi Bakufu to Ryoshun Imagawa, a military commander to ban the “evil party,” Akuto, that is the Japanese who invaded the Korean peninsula, shows the recognition of Japanese pirates and attempts in subduing them, despite being amidst the civil wars of the Nanboku-chō period (1336–1392).

The destabilising nature of the civil wars encouraged the involvement of military elites and warrior families to collude with pirate bands to “supplement their war chests through plunder, rice and captives.” Within just two decades, “overseas freebooting became a way of life along the entire coast of Western Japan.” This motivation proved to be an obstacle for authorities to work with elites and powerful clans to suppress piracy.

It cannot be said that the Korean military simply pleaded and waited for help to arrive. In August 1263, Korean officials were said to have questioned the pirates and found that they were Japanese from Tsushima Island. Products confiscated include 20 seok of rice, 30 seok of barley, and 70 pieces of cowhide.

Intensification of Wokou Attacks

However, the sheer number of attacks was too much for Korea to handle, especially with their military power being focused on Mongol presence. This left the coasts of Korea weak and unprotected, along with Korea’s geographical proximity to Japan - making it an ideal target for opportunistic raiders to exploit its weakened military and economic state. Raids on Korea’s grain supply systems, caused massive disruptions to their food production, coastal habitation, and security.

As Wokou operations grew more complex, their tactics evolved. Inland attacks began to emerge, suggesting not only a familiarity with Korean terrain but also an intentional avoidance of areas with defensive posts and military presence.

According to Hazard, pirates utilized placards, maps, and spies to gather intelligence, which allowed them to conduct surprise attacks and employ cavalry raids, expanding their reach deep into the countryside. Seoh compiled a table based upon the number of attacks noted across various chronicles. According to his table, the decade between 1375 and 1385 was the most intense period of pirate aggression - 1377 had witnessed 54 invasions.

Table of invasions recorded according to the Sejong Annals, originally compiled by Takeo Tanaka, with additions from M. S. Seoh. Taken from M.S. Seoh, “A Brief Documentary Survey of Japanese Pirate Activities in Korea in the 13th-15th Centuries,” 34.

Korea demands the crackdown of Japanese pirates. Goryeo-sa entry in June, 1377, during the reign of King Woo (1374-1388). Image and descriptions courtesy of National Institute of Korean History, Database of Korean History: Goryeo Era. Accessed April 15, 2025. https://db.history.go.kr/goryeo/

1377 Goryeo-Japan Responses

The impact of the wokou on Korea is also evident in its letters to Japan. A letter from June 1377 reveals that ever since the pirates began to appear in 1350, their presence and attacks have made Korean islanders’ conditions unlivable.

It is also noted that since 1374, the pirates have also been in full force. Japan’s reasoning with Goryeo in August 1377 that “the band of bandits are a group that fled from us and do not follow our orders, so it is not easy to restrain them,” was perceived by Goryeo to be a claim of non-responsibility. In their response the following month, Korea frames itself as a responsible and disciplined state.

This was a deliberate contrast between the two military powers. In essence, Korea is saying that despite being surrounded by strong external powers, they were able to maintain military readiness. This was a subtle criticism to Japan for not being able to do the same. Korea also attributes the success and boldness of the pirates to Japanese negligence, suggesting that pirates were taking advantage of the weak coastal defences.

"Korea is connected to Won in the north and Ming to the west, so we always train military officers and defend them. Therefore, the pirate’s bedding is only in the defense of the states of the sea. Because of that, the pirates peeked at the gap and suddenly invaded, burned private houses, plundered people and as soon as they saw our government, they immediately got on a boat and ran away and hid, so the damage was not small."

Three stories exemplifying Korean values were said to be inscribed on a stone memorial by Jo Jun. Goryeo-sa entry in June, 1382, during the reign of King Woo (1374-1388). Image and descriptions courtesy of National Institute of Korean History, Database of Korean History: Goryeo Era. Accessed April 15, 2025. https://db.history.go.kr/goryeo/

The Cruelty of the Wokou

(as portrayed by Goryeo)

Such a description of the pirates portrays them as opportunistic cowards who thrive only in the absence of authority. This then reinforces the idea that serious efforts from Japan would deter them because as soon as an organised authority appears – just like the Korean military did - the pirates would flee.

Beyond this portrayal, Goryeo’s people also perceived the Japanese as cruel savages. In a 1382 Goryeo-sa entry, three stories were noted to have been recorded and publicly memorialized by Jo Jun in stone inscriptions. They were deliberate commemorations of Korean virtue in the face of Japanese cruelty.

It is important to analyse these stories to see how Goryeo utilised the brutalities to position themselves as morally superior, and the wokou – and by extension the Japanese - as morally inferior. The story of Cho Hee-sam’s sacrifice, where he died shielding his mother from being killed by pirates, portrays him as a filial son; Bae Jung-sun’s daughter, who chose death over the possibility of capture or dishonor, as a righteous woman; the daughter of General Sinsacheon, who resisted her captor even after her father was killed, as a loyal daughter.

Jo Jun enacted stone memorials as “the loyalty and filial piety of these three people are so exceptional that it would be good to honor them by placing commendatory plaques on their households to encourage future generations.” The Japanese wokou thus became a symbol of Korea’s moral superiority and Japan’s moral inferiority.

Sal Kin Wha. Landscape. Joseon dynasty, 1392-1910. Ink and color on paper. Image courtesy of The Cleveland Museum of Art

As the Goryeo dynasty transitioned into the Joseon,

The threat of the wokou continued to solidify both in reality and symbolically. The founding of the Joseon dynasty in 1392 marked a period of reformation and state-building, yet the persistence of Wokou piracy remained a destabilizing force throughout its early years. The pirates not only posed a military and economic threat but also challenged Joseon's emerging political legitimacy and its regional relations, particularly with Ming China and Japan. The Joseon court’s responses to the Wokou were diverse, ranging from military expeditions and diplomatic strategies to cultural assertion, showcasing how piracy became a crucial factor in domestic governance and foreign policy.

One of the earliest measures under King Taejong's administration was the reorganization of naval forces to better secure the coastline. In 1418, the abdicated king ordered the subdivision of naval forces in Gyeonggi Province to “repel the Japanese pirates,” recounting how the forces “fought fiercely and intensely to crush the brunt of the pirates’ attack at Jinpo.”

This move was part of a broader militarization strategy in response to a series of coastal raids, such as the attack on a Jeju tax grain ship bound for the capital earlier that same month. The pirates' targeting of grain ships illustrates not only their desperation, likely due to poverty and resource scarcity in Japan, but also their awareness of Joseon's grain system and its vulnerabilities. This then reveals possible organised information-gathering and exchanges among pirate bands.

"Upon this, our troops divided the roads and conducted searches, seizing 129 large and small usable ships were selected, and the rest were all burned along with 1,939 houses. pirate ships. Among them, 20 pirate During the course of the fighting, 114 heads of pirates were cut off, and 21 people were captured. Grain stalks in the fields were cut down, and 131 Chinese captives were later freed."

Anti-Pirate Strategies

Joseon's response went beyond immediate defense. In December 1418, King Sejong emphasized the importance of strategically positioning competent men in power, ordering that “men with military skills and tactics be selected and appointed as local magistrates in coastal areas to prepare the state against Japanese pirates.”

This reveals an institutionalization of anti-pirate defense, recognizing that Wokou attacks now involved organized military or maritime knowledge rather than random raiding. Robinson also highlights how Japanese traders, with networks to the Joseon capital, were restricted to specific sea routes to reduce the possibility of their attacks, and to reinforce public safety. This exemplifies how Joseon state attempted to assert control over the wokou while maintaining trade relations with Japan.

"The Japanese people in Tsushima Island are bloody and cruel, violent and fierce, and invariably take revenge back. Warships in the provinces should not be separately anchored; twenty ships should be deployed at each strategic point. for the smallest slight. Although they have now submitted out of fear, it is difficult to know to whether they will not turn For the strategic point where there is no warship, the army should be stationed to guard it and remain diligent in maintaining the beacon fire system and strict in their defense. This should be made a permanent rule.

The Japanese people in Tsushima Island are born into arms and armor and view death as if it were a return home. Not engaged in farming, they steal and rob for a living. Although now reduced to near extinction, people of their kind living in other islands are numerous. Also, it is not yet known whether their submission is true or false. If they seek to involve other people of their kind in yet more raiding, this could lead to a calamity that is even more atrocious than before. Truly, this should not be carelessly dealt with."

Threat of the Wokou: Real and Symbolic

Despite this assertion – fear and uncertainty continued to shape state policy. Even after successful engagements with pirates, officials expressed caution. Yu Jeonghyeon warned in 1419 that while the people of Tsushima “have now submitted out of fear, it is difficult to know whether [they] will not turn back,” describing them as “bloody and cruel, violent and fierce.” The state’s ongoing anxiety about a resurgence of piracy led to preventive measures like building fortified communal “stations” to protect coastal populations from surprise attacks. These plans also acknowledged how past peace had ironically made people more vulnerable by encouraging dense settlement and cultivation near the shore.

Militarily, the scale of Joseon’s response peaked in 1419 with the Gihae Eastern Expedition to Tsushima Island. Sejong’s forces “seized 129 large and small pirate ships… burned [the rest] along with 1,939 pirate houses,” and “cut off 114 heads [of pirates]” while freeing “131 Chinese captives.” This expedition represented more than military retaliation — it was a projection of state power, to restore security just as much as disrupting their base of operations. Yet this show of power also reveals the tension between control and contingency. Yi Gak’s memorial from August 1419, warning that pirate ships “number in the hundreds” while each port had “not more than five to six ships at most,” underscored Joseon’s inadequate naval capacity. His call to build more warships was urgent, indicating that while the state claimed victory, it remained aware of its own structural weaknesses.

Beyond military efforts, cultural production served as another medium for asserting dominance. In November 1418, King Sejong commissioned Byeon Gyeryang to compose lyrics to a court music piece celebrating the surrender of pirates. This ceremony credited the suppression of the long-standing piracy to the virtuous ruler, which in turn legitimised his reign. Such strategies extended to Joseon’s diplomacy as well. When confronted with a case involving a Chinese woman abducted by the Japanese, King Sejong took swift action to return her and prevent the Japanese from “coming up to the capital,” reflecting his commitment to the order where Korea upheld moral hierarchy by aiding China and distancing itself from the Japanese “barbarians.”

The Joseon court consistently sought to frame the Wokou not only as a threat but also as a subdued other. Upon ascending the throne, King Sejong declared: “pirate marauders offer tribute and pledge subservience to our state,” using the containment of piracy as proof that “civil administration thrives, and our military prestige rises.” This rhetorical move reveals how the state used the Wokou issue to affirm its strength and stability, even as its military and coastal defenses were still being solidified. Thus, the pirate threat was both real and symbolic, their suppression a means for Sejong and his predecessors to assert state control, fulfill tributary obligations, and solidify their rule in such a precarious geopolitical moment.

"The capital and provinces are in order and at peace; the storehouses are abundant and full, pirate marauders offer tribute and pledge subservience to our state, civil administration thrives, and our military prestige rises. Just as the mesh of the net expands when raised from the water, the proprieties flourish and music is perfected throughout the land. Father King’s profound benevolence and generous grace inspired the people’s hearts while his grand accomplishments and magnificent achievements deluge the chronicles. This unprecedented pinnacle of peace has now lasted almost twenty years..."

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