Rethinking Sakoku: Soichi Suzuki on Japan's 'Closed Country' as a Strategy for Survival

Japan's Edo-period (1600-1868) sakoku (鎖国) policy, often translated as "national seclusion," has long been portrayed as a symbol of Japan's isolationist past. But historian Soichi Suzuki, author and representative of the Bakumatsu-shi o Minaosu Kai (Association for the Reexamination of Bakumatsu History), argues that this common image misses the point entirely.

In an interview with JAPAN Forward, Suzuki described sakoku not as isolation, but as a deliberate act of national defense. The Tokugawa shogunate, he explained, was responding to a global environment dominated by Catholic colonial expansion. "It was not a closure," he said. "It was a strategic choice to protect Japan from indirect invasion by Christian powers."

A Defensive Wall Against Imperial Faith

To Suzuki, the sakoku edicts were not born of xenophobia but of careful statecraft. The Tokugawa government, he said, understood that Spain and Portugal used Christianity as the first step toward colonization: missionaries arrived first, soldiers followed, and soon after came the loss of sovereignty. "The Iberian powers spread Christianity first," Suzuki noted, "then incited uprisings and replaced local rulers to bring territories under papal control. Japan simply refused to follow that pattern."

That refusal, however, did not mean hostility to all outsiders. Protestant powers like the Netherlands and England, which sought trade rather than religious converts, were allowed limited access through ports such as Nagasaki. The Tokugawa shogunate, Suzuki emphasized, drew a clear line between commerce and coercion, accepting the former, rejecting the latter. In his words, sakoku was "national defense conducted through diplomacy rather than war."

Hideyoshi's Ban on Slave Trading

Suzuki traced the origins of sakoku back to Toyotomi Hideyoshi, whom he described as "the father of slave emancipation." Having risen from peasant status himself, Hideyoshi was horrified to learn that Christian daimyo (feudal lords) in Kyushu, among them Arima Harunobu, Omura Sumitada, and Otomo Sorin, were selling Buddhist captives into slavery. They traded people to Portuguese merchants in exchange for guns and gunpowder.

*Toyotomi Hideyoshi (Wikimedia Commons)*

When reports reached him that Japanese people were being sold overseas, Hideyoshi banned the trade and issued the 1587 Bateren Edict (Christian Expulsion Edict). The policy, Suzuki said, is often misunderstood as anti-Christian persecution. In reality, it was an effort to stop human trafficking.

Hideyoshi even told missionaries they could continue their faith quietly if they ended the slave trade. "That was his real intent," Suzuki explained. "He was defending human dignity as much as sovereignty."

The San Felipe Incident and the Spanish Threat

Suzuki cited the San Felipe Incident of 1596 as the decisive moment that turned Japanese caution into conviction. When the Spanish galleon San Felipe ran aground off Tosa and its cargo was seized under Japanese law, the ship's pilot reportedly boasted that Spain conquered the world by sending priests first and armies later.

"Hideyoshi was furious," Suzuki explained. The claim confirmed his suspicion that religion served as an instrument of empire. In its aftermath, the execution of 26 Christians in Nagasaki, he added, should be understood not as blind persecution but as a direct response to this perceived threat.

"From that moment," Suzuki said, "Japan understood that religion could be a weapon of invasion."

Internal Jesuit Disputes and the Road to Sakoku

The historian pointed out that internal divisions within the Jesuit order also shaped Japan's fate. Missionaries in Asia were split over whether to prioritize the conversion of China or Japan. Jesuit Gaspar Coelho advocated the military conquest of Japan with the support of Christian daimyo, while Alessandro Valignano, the order's regional superior, urged patience and diplomacy. These debates, Suzuki argued, revealed how Japan had become a central target of the church's imperial strategy, not just another mission field.

When the Tokugawa regime rose to power, it inherited these bitter lessons. Determined to prevent another foreign foothold, it implemented strict controls over religious activity and foreign entry.

From Ieyasu to Iemitsu: The Logic of Controlled Trade

Under Tokugawa Ieyasu, Japan continued to engage with European traders, though always under careful supervision. Ieyasu permitted Spanish and Portuguese commerce through Kyushu, but soon realized this arrangement concentrated too much wealth and influence among Christian lords in the south. To balance power, he shifted trade eastward, granting land to English navigator William Adams and promoting exchange through ports like Uraga in Tokyo Bay.

By the reign of Tokugawa Iemitsu, the third shogun, infiltration by Catholic priests and secret Christian networks had become impossible to ignore. Suzuki explained that Jesuit correspondence from this period explicitly outlined a plan to foment rebellion among Japan's estimated 600,000 Christians.

"Iemitsu understood what was at stake," he said. "He declared that even the loss of a tiny piece of Japanese territory to a foreign power would be a national disgrace." To Suzuki, this stance epitomized true leadership — "a ruler willing to lose his power, but not his country."

The Shimabara Rebellion

Many often simplify the Shimabara Rebellion (1637–38) as a peasant uprising. However, in Suzuki's view, it was the final act in a long struggle between Japan and Catholic imperialism. While many textbooks portray it as a revolt by overtaxed farmers in Kyushu, Suzuki argued that such descriptions overlook the movement's religious and geopolitical dimensions. "It wasn't just a tax revolt," he said. "It was an armed insurrection with foreign backing, a direct result of years of underground missionary work."

Led by young Christian figure Amakusa Shiro, the rebels fortified themselves in Hara Castle, flying Christian banners and awaiting aid that never came. Suzuki pointed out that the rebellion was concentrated in territories formerly ruled by Christian daimyo, where the Jesuits had long maintained covert networks. "The revolt spread precisely in regions that had been under Catholic influence," he explained. "These were not accidental locations. They were the remnants of the old missionary strongholds."

The Tokugawa shogunate, alarmed by the scale of the uprising and the reemergence of Christian symbols, mobilized an enormous force of over 120,000 troops. After a brutal siege lasting several months, they took Hara Castle and annihilated the rebels.

End of Foreign Influence

For Suzuki, the crushing of Shimabara was not merely a domestic act of suppression, but the moment Japan decisively severed itself from the orbit of European power.

"From the shogunate's perspective," he said, "Shimabara was proof that the danger had never truly disappeared. Missionaries had continued to infiltrate, to organize, and to dream of rebellion. Sakoku became the firewall that prevented Japan from becoming another colony."

In the wake of the rebellion, the shogunate expelled all Portuguese, outlawed Christian practice, and reduced contact with the outside world to tightly managed trade through Nagasaki. What followed was two and a half centuries of unprecedented peace, what Suzuki called the Pax Tokugawa.

Isolation, Industry, and the Foundations of Growth

Suzuki challenged the idea that sakoku stifled Japan's progress. On the contrary, he said, the long peace allowed domestic industries to flourish and innovation to take root. Deprived of imports, local artisans developed Japanese-made substitutes for foreign goods such as sugar, dyes, and textiles. "Without foreign trade," he explained, "Japan became self-sufficient. People learned to make what they needed. That stability allowed economic growth and craftsmanship to flourish."

He argued that this economic independence laid the groundwork for Japan's rapid modernization after the Meiji Restoration, proof that controlled isolation could serve as a stage for self-reliance rather than stagnation.

Lessons for the Present

Asked whether sakoku might be compared to modern protectionism, Suzuki rejected the idea that it was an emotional or ideological policy. Instead, he described it as pragmatic statecraft shaped by circumstance. "Strong nations advocate free trade because it benefits them most," he said. "When they weaken, they turn to protectionism."

He drew parallels with Britain's bloc economies after World War I and America's recent tariff increases under Trump, arguing that both reflected the same underlying logic of self-preservation.

"For nations," Suzuki concluded, "there is a time to open and a time to close. Sakoku was not Japan turning its back on the world — it was Japan defending its right to exist within it."

Author: Daniel Manning