The Keichō Campaign (Second Korean Invasion)

In the first month of Keichō 2 (1597), Toyotomi Hideyoshi dispatched a massive army to Korea once more. This decision came as peace negotiations—ongoing since the Bunroku Campaign (1592–93)—had collapsed. This second expedition became known as the 'Keichō Campaign,' and when combined with the Bunroku Campaign, it is recorded in Japanese history as the 'Bunroku-Keichō Wars.'

The Campaign's Course and Second Crossing

In the first month of Keichō 2, vanguard forces including Konishi Yukinaga, Katō Kiyomasa, and Kuroda Nagamasa—totaling approximately 140,000 troops—crossed to Korea once more. Having suffered from fierce resistance by Korean forces, volunteer militias, and Ming relief armies during the Bunroku Campaign, the Japanese now prioritized securing the southern coastline and establishing defensive strongholds as their strategic pillars.

In initial engagements, Japanese forces advanced favorably, capturing Namwon Castle (Keichō 2, 8th month) and occupying Jeonju. However, Korean civilian resistance and the revival of the Korean navy under Admiral Yi Sun-sin began to strangle Japanese supply lines. Yi Sun-sin, imprisoned on false charges after the Bunroku Campaign, was restored to command following the catastrophic Korean naval defeat at the Battle of Sacheon (Keichō 2, 7th month), and he faced his final battle as a legendary commander.

The Siege of Ulsan Castle—Katō Kiyomasa's Desperate Stand

From Keichō 2, 12th month, through the 2nd month of the following year, Ulsan Castle, held by Katō Kiyomasa, was surrounded by a massive combined force of Ming and Korean armies. Food and water in the castle were quickly exhausted, and Kiyomasa's forces were driven to slaughter horses and endure extreme hardship.

During this siege, the practical value of the Japanese sword was brought into sharp relief. In close-quarters combat along the castle walls, the katana proved decisive in matters of life and death. While Katō Kiyomasa's famous large jūmonji-yari (cross-shaped spear) is well known, the katana worn at the waists of his retainers likewise saw their blades crossed repeatedly in days of relentless close combat.

The siege by the combined Ming and Korean forces was broken in the first month of Keichō 3 (early 1598) by relief armies led by Mōri Hideaki and Kuroda Nagamasa, and Kiyomasa held the castle firm until that moment. This siege became a legendary expression of Japanese samurai spirit and cemented Katō Kiyomasa's legendary status in posterity.

Nabeshima Naoshige and the Sword Culture of the Daimyo

Many sengoku daimyo participated in the Korean campaigns, each carrying renowned swords across the sea. Nabeshima Naoshige of Hizen is remembered for conducting tiger hunts in Korea and is famous for returning with Korean potters who became the foundation of Hizen ware. However, examples also exist of Japanese commanders bringing back Korean swords.

Named blades carried by Kuroda Nagamasa and swords associated with Shimazu Yoshihiro have attracted the attention of researchers as contact points between Kyushu's sword culture and continental metalworking traditions. Swords captured on the Korean and Ming battlefields may have provided Japanese sword smiths with technical stimulus, as scholars have noted.

Particularly noteworthy is the practical combat blade known as the 'Dōtanuki,' produced in Higo (Kumamoto) in Kyushu. The Dōtanuki, known as a sturdy, utilitarian weapon prioritizing function over refinement, is recorded as having been wielded by samurai under Katō Kiyomasa's command during the Korean campaign. In the chaotic, close-quarters combat that unfolded on Korean battlefields, the value of this type of practical blade stood out.

The Battle of Noryang and Admiral Yi Sun-sin's Death in Combat

When Toyotomi Hideyoshi died on the 18th of the 8th month of Keichō 3 (1598), the Council of Five Elders and Five Commissioners decided to withdraw. However, the retreat operation proved far from simple. To safely evacuate 140,000 troops scattered across fortifications throughout the peninsula, the Japanese had to neutralize interference from the Korean and Ming navies.

In the 11th month of that year, a final major sea battle erupted in the Noryang Strait (near present-day Namhae Island). Fleets under Shimazu Yoshihiro, Tachibana Muneshige, and Sō Yoshitoshi collided with the combined fleet commanded by Chen Lin and Admiral Yi Sun-sin.

In this battle, Yi Sun-sin was struck by a stray bullet and fell in combat. His final words—'Do not let the enemy know of my death'—are remembered to this day. The fleet under Shimazu Yoshihiro broke through in a desperate action, and many Japanese army units succeeded in escaping. However, both sides suffered catastrophic losses.

Cultural Influence and Swords

After the Keichō Campaign's conclusion, Japan received numerous cultural influences from Korea. The transfer of ceramic technology—notably Satsuma ware, Arita ware, and Hagi ware—is well known. However, the sword disciplines also warrant attention.

The combination of large quantities of tanegashima (matchlock firearms) and Japanese swords that the Japanese army introduced posed a tactical question on the battlefield: the fusion of close-quarters combat and long-distance volleys. This experience exerted influence on early-Edo-period debates over military doctrine—whether to prioritize the refinement of swordsmanship or the proliferation of firearms.

Moreover, sword smiths (official retainers of each domain) who garrisoned in Korea and conducted repairs and manufacture of blades on the battlefield left swords scattered throughout the Korean Peninsula. Conversely, records remain showing that Ming metalwork and the ring-pommel sword style of the Li Dynasty flowed into Japan, and some Japanese smiths absorbed foreign techniques.

Rendered purposeless by Hideyoshi's death, this war concluded while leaving indelible wounds across the Korean Peninsula. Yet the brutal record of those seven years remains an important research subject in both sword history and military history, marking the final large-scale instance of the Japanese sword's deployment in an East Asian-scale international war.