In the 1570s, Chōsokabe Motochika launched a campaign to personally unify Shikoku, the smallest of Japan's four main islands, and defeated a number of samurai rivals over the next decade.

In 1584, Hideyoshi won a political victory against Tokugawa Ieyasu at the Battle of Komaki and Nagakute, securing his position as paramount warlord.

Chōsokabe chose to fight to defend his territories with his force of 40,000 men, despite the overwhelming size of Hideyoshi's army and the suggestions of his advisors to submit.

[2] Awa was given to Hachisuka Iemasa and Akamatsu Norifusa, Sanuki was given to Sengoku Hidehisa and Sogō Masayasu, and Iyo was given to Kobayakawa Takakage and other Mōri generals.

Chōsokabe submitted as a retainer and general of Hideyoshi, participating in the Kyūshū campaign and Japanese invasions of Korea, and later became known for his involvement in the San Felipe incident.