Shimabara Rebellion
Final assault destroys the Shimabara rebels at Hara Castle
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Original prompt & settings (JSON) ↗The Dutch fired 426 cannon rounds into Hara — then withdrew a month before Japanese troops stormed it.
12 April 1638, at a ruined castle
Tokugawa forces launched their final assault on the rebels' stronghold — the ruined Hara Castle on the Shimabara Peninsula — on 12 April 1638. Information reaching the besiegers indicated the defenders' food and ammunition were nearly spent.
About 30,000 people had crowded into the abandoned fortress: peasants, former samurai, Christians, and their families. The hunger-weakened defenders were overwhelmed, and the fall of Hara ended organized resistance.
Where the Dutch were
At the shogunate's request, the Dutch East India Company factor Nicolaes Couckebacker had reluctantly supplied naval and shore bombardment earlier in the siege — 426 rounds fired into Hara between 24 February and 12 March 1638.
They withdrew on 12 March and took no part in the storming.
12 April, or 15 April
The capture was followed by a massacre of the remaining rebel population, which included combatants, women, and children. The rebels' religious and symbolic leader was the youth Masuda Shirō, commonly called Amakusa Shirō.
The anniversary depends on where a historian draws the line. The strongest scholarly source dates the assault and the fall of Hara to 12 April, while some modern chronologies carry surviving resistance and killing through 15 April.
Sources
Researched 23 Aug 2026 6 sources not yet audited Date disputed
How this was checked
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Date disputed. Sources disagree; the research places it at 1638-04-12.
What the sources leave uncertain
- The listed 15 April date is not the date used by the strongest scholarly event source consulted, which dates the final assault and fall of Hara to 12 April 1638.
- Some modern chronologies describe outer defenses falling on 12 April and surviving resistance or killing continuing until 15 April. The discrepancy therefore partly reflects whether the event is defined as the storming of Hara or the end of the subsequent fighting and massacre.
- Japanese accounts also preserve dates in the Kan’ei lunisolar calendar, creating additional conversion and event-boundary confusion.