Shikoku Campaign—Chosokabe Motochika's Surrender and Toyotomi Hideyoshi's Acceleration Toward Nationwide Unification

The "Shikoku Campaign" conducted in July of Tensho 13 (1585) was the military operation in which Hashiba Hideyoshi (Toyotomi Hideyoshi) forced Chosokabe Motochika—who had unified Shikoku—to surrender, marking a major turning point in the pacification of the western provinces. In Hideyoshi's project to unify the realm under his rule, it was an important military action alongside that same year's Kishu Campaign (conquest of Negoroji Temple and the Saiga ikki), and it also laid the groundwork for the Kyushu Campaign of Tensho 15 (1587), which resulted in the Shimazu clan's surrender.

Chosokabe Motochika and the Unification of Shikoku

Chosokabe Motochika (1539–1599) began as a regional daimyo in Tosa Province (present-day Kochi Prefecture) and unified Tosa by defeating Ichijo Kanetsada at the Battle of the Taokawa (Shimanto River) in Tensho 3 (1575). He subsequently expanded his domain rapidly across all of Shikoku, and by around Tensho 11 (1583) had conquered the majority of Iyo, Sanuki, and Awa provinces, achieving nearly-complete unification of Shikoku.

Motochika excelled not only in military strategy but also possessed refined cultural cultivation and devoted himself to developing local industries and agriculture in Tosa. There are few records of sword smiths from Tosa, but it is believed that the blades used by Motochika's forces were procured from major production centers such as Echizen, Bizen, and Yamato, and it is said that Motochika himself kept high-quality swords at hand.

The Path to Conflict with Hideyoshi

Initially, Motochika maintained a good relationship with Oda Nobunaga and was tacitly permitted to pursue his Shikoku ambitions, even though Nobunaga sarcastically called him "the bat on an island without birds." However, when Nobunaga died in the Honnoji Incident of Tensho 10 (1582), a succession struggle broke out (the Battle of Yamazaki and the Kiyosu Conference). As Hashiba Hideyoshi moved to seize real power, the question of how to deal with Motochika became problematic.

From Tensho 11 (1583) onward, Hideyoshi began to move toward solving the Shikoku problem. Hideyoshi demanded that Motochika return Sanuki, Awa, and Iyo provinces, but Motochika refused. During the Battle of Komaki-Nagakute of Tensho 12 (1584)—Hideyoshi versus Tokugawa Ieyasu—Motochika briefly showed signs of alignment with the Tokugawa and Oda Nobutaka factions, but when that battle ended in settlement, Motochika found himself increasingly isolated.

The Unfolding of the Shikoku Campaign—A Three-Pronged Invasion

In June of Tensho 13 (1585), Hideyoshi completed the organization of the Shikoku expeditionary force. The main army of approximately 60,000 troops, commanded by Hashiba Hidenaga (Hideyoshi's younger brother), invaded from Sanuki, while a separate force under Ukita Hideie advanced from the Awa-Sanuki border, and Hashiba Hidetsugu attacked from Awa—a three-pronged simultaneous invasion was adopted. The total force is estimated at approximately 100,000 troops.

Motochika attempted to construct defensive lines by stationing castles throughout the region, but in the face of overwhelming numerical superiority, castle after castle fell or surrendered. The Kawano clan of Iyo, the Kagawa clan of Sanuki, and remnants of the Miyoshi clan in Awa had already surrendered to Hideyoshi's faction, leaving Motochika isolated and without support.

On the 25th day of the 7th lunar month, Chosokabe Motochika resolved to surrender. His second son, Kagawa Chikaau (who had been continuing the Kagawa clan of Sanuki), had already surrendered to Hideyoshi's forces, and Motochika accepted settlement under the condition that he would be confirmed in possession of Tosa Province alone.

The Blade-Historical Significance of the Shikoku Campaign—Settlement Through Negotiation With Minimal Combat

The Shikoku Campaign, in fact, involved little large-scale hand-to-hand combat. Faced with the 100,000-strong force, Chosokabe-held castles surrendered one after another without firing a shot, and Motochika himself avoided pitched battle, agreeing to terms instead. This was a textbook example of Hideyoshi's method of "imposing diplomacy through an ostentatious show of military force," and at this stage there was scarcely any occasion for extensive use of blades in actual combat.

However, the indirect impact of the Shikoku Campaign on sword history was substantial. With Motochika's surrender, Shikoku fell under Hideyoshi's control, and the Sword Hunt Edict (katanagari) of Tensho 16 (1588) was extended to Shikoku as well. By dismantling the Chosokabe clan's powerful indigenous armed forces and disarming the peasantry and general populace, Tosa's structure of sword ownership underwent dramatic change.

The swords carried by officers and soldiers who participated in the Shikoku Campaign are believed to have been primarily blades from western Japanese production centers such as Bizen, Mimasaka, Harima, and Yamato. Hideyoshi's directly controlled forces were in a period of military buildup in anticipation of the Korean campaigns (the Bunroku and Keicho invasions), during which large quantities of swords, spears, and firearms were procured and prepared.

The Chosokabe Clan's Movements After the Shikoku Campaign

Motochika, enfeoffed in Tosa Province alone, served as Hideyoshi's retainer and participated in the Korean campaigns (the Bunroku and Keicho invasions). Motochika's descendants sided with the Western Army (Ishida Mitsunari faction) at the Battle of Sekigahara (1600), and after their defeat, the Chosokabe clan was stripped of their lands. Tosa was granted to Yamauchi Kazutoyo (Tosa Domain), and the Yamauchi family's rule continued until the end of the Edo period.

As for swords associated with Motochika, the tradition of Tosa sword smiths in Tosa Yamada (present-day Kami City, Kochi Prefecture) is said to have been maintained throughout the Motochika period. Tosa blades (works by Tosa-born sword smiths) earned a certain reputation in the Osaka blade market during the Edo period as "Tosa goods," transmitting one aspect of the martial legacy of the Chosokabe clan to the present day. The Kochi Castle History Museum (Kochi City) houses and displays armor, sword fittings, and related items connected to Chosokabe Motochika, offering a glimpse into the martial equipment culture of the time of the Shikoku Campaign.