Photo/IllutrationIn this letter, Toyotomi Hideyoshi calls on Wakizaka Yasuharu, a vassal warlord who took part in Hideyoshi’s invasion of Korea, to quickly join the forces of Konishi Yukinaga, a fellow warlord. (Asahi Shimbun file photo)

  • Photo/Illustraion

Warlord Toyotomi Hideyoshi (1537-1598) twice invaded Korea not because of a megalomaniacal desire for new territory but because he wanted to thwart Spanish and Portuguese plans to dominate Asia, according to a historian.

Arata Hirakawa, president of Miyagi Gakuin Women’s University, who specializes in early-modern Japanese history, has come up with a theory that challenges the long accepted view of the motivations of the warlord who unified Japan.

While the ultimate goal—conquest of China’s Ming Dynasty—is the same in the two theories, the need for such aggression differs.

The military action into Korea comprises two phases: the Bunroku War, which began in 1592 and ended with a truce in 1593, and the Keicho War, from the resumption of hostilities in 1597 through the final withdrawal of the Japanese troops in 1598.

Conventional theories say that Hideyoshi, who had risen to the status of “kanpaku” (chancellor to the emperor), needed more land to give to his vassals as a reward.

Hirakawa’s theory, described in “Sengoku Nihon to Dai Kokai Jidai” (Warring states in Japan and the age of discovery), a book published in April, says Hideyoshi sent troops to Korea to counter the dominance over Asia by Spain and Portugal, which were the global hegemonic powers at the time.

The two Iberian powers in 1494 signed the Treaty of Tordesillas, agreeing to demarcate their turfs for dividing and ruling the world. This set off moves to expand their respective territories.

The Portuguese built footholds in Calicut and Goa, both in India. They also attacked Malacca and brought the city on the Malay Peninsula under their control.

The Spanish sent a fleet to the Philippine island of Cebu and occupied Manila.

Soon, both powers set their sights on Japan.

Francisco Xavier of the Society of Jesus (Jesuits), a group of missionaries with Portuguese connections, landed on Kagoshima in 1549. Members of the Franciscan Order, which had ties with Spain, arrived in Japan in the 1580s.

Numerous scholars believe that many of those missionaries, who worked hard to promulgate the Catholic faith, were the “vanguard of conquistadores.”

Gaspar Coelho, vice provincial of the Jesuits in Japan, said in a letter sent in 1585 to the rector of the Jesuit mission in the Philippines, “As soon as possible ... you could kindly send ... frigates well equipped with people, ammunition and artillery ... with the help of the local Christian lords, they will be able to ... bring so much terror to the enemies that they will no longer dare to make moves.”

Hirakawa said Coelho’s ambition was to convert feudal lords in Japan and draw on their military forces to conquer Ming China.

“The missionaries believed that Christian feudal lords would follow their directions faithfully, and they were therefore apparently optimistic about the prospect for dominating Japan,” Hirakawa said.


Hideyoshi was likely also wary of the Jesuits’ ambitions.

Hirakawa believes that Hideyoshi’s 1587 Edict of Expulsion of the Padres, which ordered the deportation of Christians, was aimed at expelling the military forces of the missionaries and their hold over believers.

The military expedition to Korea began amid that succession of developments.

Hideyoshi was told in May 1592 at Hizen Nagoya Castle in today’s Karatsu, Saga Prefecture, that Hanseong, Korea’s capital and today’s Seoul, had surrendered. He then sent letters, including to nephew Hidetsugu (1568-1595), to describe his next plans.

The letters say that once Ming China has been taken, Hidetsugu would be named chancellor of the conquered areas. Hideyoshi himself would set up residence in Ningbo, a Chinese city that was a trade hub across the East China Sea, with a further ambition to bite into India.

Around the same time, Hideyoshi also called upon Ryukyu (Okinawa) and Formosa (Taiwan) to subjugate themselves to Japan. And he sent multiple letters with intimidating passages to the Spanish governor of the Philippines.

“You should bring down the flag and recognize (my) lordship,” he wrote in one of the letters. “Many captains have asked me to give them permission to go and take Manila,” he said in another.

“Hideyoshi’s objective did not simply stop with invading Korea but lay in subjugating China, India and Southeast Asia further along the way,” Hirakawa said. “Hideyoshi once denounced the Philippine governor, saying in one of his letters that the promulgation of the Catholic teaching is a ruse and deception with which to take hold of other countries.

“While the Spanish and the Portuguese had an ambition to conquer Japan under the guise of missionary work, Hideyoshi was attempting to subjugate those Europeans on the contrary.”

In fact, Hideyoshi’s tough foreign policy stance and his rumblings of possible military action were apparently perceived as threats.

A messenger of the Philippine governor, out of fear that Manila had become a target of Hideyoshi’s attacks, said in a letter to an inspector in Manila, “It is very important for Manila to ... make the rampart bigger.”

Before Hideyoshi took power, arguments had increased in Spain and Portugal for conquering Japan, but these views died down after Japan invaded Korea.

“Although I am in no way endorsing the act of invading another country, the military expeditions to Korea may have ended up prompting Spain to change the course of its diplomacy,” Hirakawa said.

Period dramas portray Hideyoshi as a person who became enfeebled and made frequent misjudgments late in his life. There are, however, no primary historical documents that substantiate that viewpoint.

Hirakawa’s theory calls for reinterpreting Hideyoshi’s diplomacy in the light of the global affairs of the time.


Tokugawa Ieyasu (1543-1616), who unified Japan after Hideyoshi’s death, is referred to as the “emperador” (emperor), not as a “rey” (king), in historical documents of correspondence between missionaries and their home countries. Japan, likewise, was referred to as an “imperio” (empire).

In Europe at the time, only the ruler of the Holy Roman Empire used the title of “emperor.” Both Britain and France were only “kingdoms,” which were one rank lower, whereas Ieyasu was being treated as an equal of the Holy Roman Emperor.

Provincial lords of Japan were being compared to kings. For example, Date Masamune (1567-1636), a ruler of today’s Sendai area, was the “Rey de Voxu” (King of Oshu).

Hirakawa said he believes the Europeans formed their view of Japan as an “empire” with strong military forces during the reigns of Hideyoshi and Ieyasu. Japan, during the closing years of the feudal age, was counted as one of the “seven empires of the world,” alongside China, Russia, India (Mogul), Persia, Turkey and the Holy Roman Empire.