Tokugawa Japan: Reading 4--Invasion of Korea, Sakoku and Christianity

The Tokugawa Shogunate (1603-1868)

Guiding Questions:

What challenges did the 3 Unifiers of Japan and the Tokugawa Shogunate face? 

How did they centralize power?

 

 Section 4: Invasion of Korea, Sakoku and Christianity

Although the period you are reading about this week was defined by Japan’s strict isolation from the outside world, it began with not one, but two disastrous invasions of Korea. Hideyoshi, Japan’s second Unifier, invaded Korea in 1592 and 1598 as a stepping stone towards his ultimate goal of conquering China. 

Hideyoshi once claimed that when he was born, a great light flooded the room and a divine voice told his mother, “When he reaches the prime of life, his virtue will illuminate the four seas, his authority will emanate to the myriad peoples.” The “four seas” is a reference to the Japanese belief at the time that there were only three great nations in the world–China, Japan and India. Therefore, this quote is interpreted by most historians as a desire for world domination through the conquest of China and India. 

Hideyoshi’s idea was deeply flawed, given the mismatch between Japan’s population and resources and China’s, but it wasn’t as crazy as it might sound. China’s Ming dynasty looked weak (it fell a few decades later, in 1618). Korea had ineffective leaders and deep divisions between its nobility and ordinary Koreans. After a century of Sengoku period war, Japan’s samurais and foot soldiers were among the most experienced, deadly troops in the world, and their access to Western firearms made them truly formidable. These advantages allowed Hideyoshi to harbor the delusion that Japanese military superiority would overcome the complex logistics of transporting 150,000 troops and their supplies to Korea in almost 1,000 ships. 

The first invasion began surprisingly well, with history’s largest sea-based invasion until D-day (June 1944) going off without a hitch. In 1592, Japanese forces quickly overran many Korean cities, including Seoul, the capital. 

Despite these early victories, the Japanese faced significant challenges as the war progressed. The first problem was Japan’s relative lack of experience in naval warfare–samurai were deadly killing machines on land, but Japan had no overseas colonies to protect or subjugate, so large scale naval battles were new to them.

The Korean navy, led by Admiral Yi Sun-sin, implemented ingenious strategies and deployed the famous turtle ships to disrupt Japanese supply lines. These ships had distinctive armored and turtle-shaped hulls, covered with iron plates and spikes, making them highly resistant to arrows, bullets, and incendiary devices. A dragon's head prow that was mounted on the front of the ship with a large mouth that emitted smoke and fire, intimidating the enemy and creating confusion. It also functioned as a cannon, capable of firing projectiles at close range. 

Turtle ships had a variety of artillery, including cannons and even early versions of rocket launchers. These weapons were strategically positioned on the ship's decks and sides, allowing for a 360-degree firing range. They were powered by a combination of sails and oars, which provided the flexibility to maneuver quickly. One of the notable aspects of the turtle ships was their ability to deploy boarding parties, who would board enemy ships during close-quarters combat. 

Admiral Yi Sun-sin, effectively used the turtle ships in numerous naval engagements, inflicting heavy casualties on the Japanese fleet. The Korean navy regained control over strategic waters, limiting Japan’s ability to support and supply their land forces.

Thus, while Japanese troops’ supply lines grew longer the more they advanced into Korea’s heavily mountainous terrain, their lifeline to Japan kept getting cut off by the Korean navy. As their advance slowed and Korean resistance stiffened, China mobilized a massive army and invaded from the North. The Chinese employed superior numbers and strategic alliances with local Korean resistance groups to drive the Japanese out. 

The Japanese fled home, only to return a few years later in a second invasion. Tens of thousands of Japanese and Chinese soldiers died, along with even more Korean civilians. Even so, Japan’s attacks on Korea only halted after Hideyoshi's death in 1598 led to confusion and low morale in the Japanese military. The end result of these foreign disasters was a conservative turn towards isolation under the Tokugawa shogunate.

During the Tokugawa shogunate (1603-1868), Japan implemented a policy known as "Sakoku," which translates to "closed country." This policy aimed to restrict foreign influences and maintain domestic stability. By isolating itself from the outside world, Japan sought to protect its unique culture and maintain control over its internal affairs. In doing so, Japan took extreme measures–shutting off trade to all but a small number of tightly controlled foreign merchants, banning any Japanese from leaving Japan or returning from abroad (the punishment for doing either was death), expelling foreign missionaries, and persecuting Japanese Christians so harshly that the survivors went underground for two centuries. 

One of the primary reasons behind Sakoku was to protect Japan from potential invasions or foreign domination. The shogunate was concerned about the growing influence of European powers, particularly after witnessing the colonization of neighboring Asian countries. Portugal had recently established colonies in India (Goa) and China (Macau), while the Dutch conquered what is now Indonesia. The enormous wealth generated by these colonies brought thousands of Europeans to Asia, many engaged in business, but some aiming to convert Asians to Christianity. It didn’t take long for Portuguese missionaries to make their way to Japan and, in the eyes of most of Japan’s rulers, take advantage of the Sengoku period to sell guns and spread their foreign religion to Japan’s daimyo. Portuguese firearms gave daimyo on the southern island of Kyushu a huge advantage over their enemies; some even converted to Christianity, which meant that all of their subjects had to do the same. 

Under the policy of Sakoku, the shogunate strictly controlled foreign trade, only allowing it with the Dutch and Chinese. Foreigners were only allowed to trade in designated ports, the most important of which was Nagasaki. While there, they had to follow strict regulations designed to limit contact between foreigners and Japanese. Sakoku was enforced so harshly that a group of patriotic samurai who secretly studied European weaponry and tactics in order to help Japan defend itself from potential European aggression were actually ordered to kill themselves for the crime of distributing foreign books and ideas. 

Another aspect of Sakoku was the expulsion of Christian missionaries. The shogunate feared that Christianity would undermine the authority of the shogun and disrupt social order. Consequently, Christians faced persecution and were banned from practicing their faith openly. This harsh repression started under Hideyoshi, who at first tried to limit, but not outright ban, Christianity’s spread. In a 1587 edict entitled “The Expulsion of Missionaries”, he wrote that: 

1) Japan is the country of gods, but has been receiving false teachings from Christian countries. This cannot be tolerated any further. 

2) The [missionaries] approach people in provinces and districts to make them their followers, and let them destroy [Buddhist] shrines and temples. This is an unheard of outrage…

3) The padres, by their special knowledge [in the sciences and medicine], feel that they can at will entice people to become their believers. In doing so they commit the illegal act of destroying the teachings of Buddha prevailing in Japan. These padres cannot be permitted to remain in Japan. They must prepare to leave the country within twenty days of the issuance of this notice.

After Hideyoshi’s death, the Tokugawa Shoguns banned Christianity outright, expelling all Europeans from Japan, with the exception of a small group of Dutch merchants in Nagasaki. Foreign missionaries who came to Japan despite the ban were arrested and crucified. All known or suspected Japanese Christians were forced to publicly renounce their religion or face the death penalty. There were tens of thousands of Japanese Christians in Kyushu at the time of Hideyoshi’s death, but just a few decades later, the few who survived without renouncing their faith had to hide it in public until the fall of the Tokugawa shogunate in 1868.