The Isshi Coup and Kōtoku's Succession

By 645, Soga no Iruka exercised unusual influence under Empress Kōgyoku. Two years earlier his forces had destroyed the household of Prince Yamashiro, a possible royal rival. The Nihon shoki describes Iruka in hostile language, but it also preserves the concrete setting in which power, royal succession and control of armed followers had become entangled. Prince Naka no Ōe and Nakatomi no Kamatari formed an alliance against him.

During a palace reception in 645, the conspirators attacked Iruka in Kōgyoku's presence. The chronicle supplies dramatic speeches and hesitation among the attackers; those details belong to a later court narrative and cannot all be treated as an eyewitness transcript. The secure action chain is narrower: the attack killed Iruka, the sovereign withdrew, and Emishi died the next day while the senior Soga residence and its records were destroyed.

Kōgyoku abdicated after the coup. Naka no Ōe did not take the throne. Prince Karu, Kōgyoku's brother, became Emperor Kōtoku, and Naka no Ōe became crown prince. Kamatari entered the ruler's close advisory circle, while Abe no Uchimaro and Soga no Ishikawamaro became the senior ministers. The settlement therefore redistributed office across several households rather than replacing Soga government with one man's rule.

Kōtoku's government moved toward Naniwa and issued measures later associated with the Taika era. The Nihon shoki presents a broad reform program, but later evidence shows a longer, less uniform process of changing ranks, land administration and local units. The coup made later action possible by changing the court's leadership. It did not enact every later rule at the moment Iruka fell.

Succession and the senior Soga house

The palace coup of 645 grew from a court in which royal succession and ministerial power could not be separated. Soga no Emishi remained chief minister under Empress Kōgyoku, and his son Iruka exercised authority through the family household and its armed dependants. In 643 Iruka's forces attacked Prince Yamashiro's household. The prince's destruction removed one possible focus for opposition and made the Soga family's role in succession newly dangerous to other court actors.

Prince Naka no Ōe, Kōgyoku's son, found an ally in Nakatomi no Kamatari. Later biographies gave their meeting a polished origin story, but the court chronicle more securely establishes their coordination in the coup. Their interests overlapped without making their later careers identical. Naka no Ōe was a royal prince with a possible claim to rule; Kamatari was a court servant seeking influence through access, advice and office.

The event is often introduced as the beginning of a national reform. That ending should not be read backward as the conspirators' complete documented plan. The immediate problem was control of the palace and succession. The administrative changes that followed required new appointments, negotiation and repeated commands over several reigns.

Attack, collapse and abdication

The conspirators chose a court ceremony at which Iruka would be exposed before the sovereign. The Nihon shoki names Naka no Ōe among the attackers and places Kamatari in the coordinated operation. It narrates fear, delay and accusation in vivid detail. Those scenes explain how the compilers wanted the overthrow understood; they do not provide a verbatim record of private planning or every word spoken in the hall.

Iruka was wounded and killed before Kōgyoku. The sovereign retired from the scene. On the following day Emishi, unable to preserve the senior household's position, died as the residence and part of its written collection burned. Other Soga connections remained at court, including Soga no Ishikawamaro. The coup destroyed a particular ruling branch rather than erasing every Soga person or relationship.

Kōgyoku then gave up the throne. Naka no Ōe declined immediate accession, and Prince Karu became Emperor Kōtoku. This was not an automatic reward to the coup's leading prince. It was a negotiated transfer that preserved royal seniority while placing Naka no Ōe as crown prince beside the new sovereign.

A new coalition takes office

Kōtoku's first government assigned visible roles across the coalition. Naka no Ōe became crown prince. Kamatari received a special inner advisory position. Abe no Uchimaro and Soga no Ishikawamaro became left and right ministers, and clerical advisers with continental learning entered the governing circle. Each appointment supplied a different resource: royal legitimacy, access to the sovereign, household followings and written administrative knowledge.

The court soon moved its political center toward Naniwa. New edicts addressed offices, land, taxation and local administration. Their wording survives in the later chronicle, while archaeology and later documents show that administrative categories continued to change. This makes the reform sequence real but uneven: commands could declare a direction before institutions operated consistently across the realm.

The alliance also developed tensions. Naka no Ōe later returned to Asuka while Kōtoku remained at Naniwa, and Kōtoku died in 654. Kōgyoku then returned to the throne as Empress Saimei. These later changes prevent the 645 settlement from being treated as a permanent partnership whose members always pursued the same policy.

A remembered beginning with uneven results

The coup altered the court's political lineage. Naka no Ōe eventually ruled as Emperor Tenji, and Kamatari received the Fujiwara name shortly before his death. Their descendants and later historians made 645 a powerful origin point. That memory should not turn later Fujiwara influence or Tenji's later policies into proof of a single plan already complete inside the palace.

Kōgyoku's role is equally important. She was the reigning sovereign before whom the violence occurred, chose abdication, remained royal mother under Kōtoku and returned as Saimei. Her career shows that abdication did not remove a former sovereign from political life. Kōtoku's reign likewise mattered as a real phase of government rather than a placeholder between two reigns of the same woman.

For HO, the event marks a change in actors and governing possibilities. It does not absorb the later Baekje war, Tenji's reign or the 672 Jinshin War, each of which has its own causes and action chain. The coup's importance lies in the succession settlement it forced and in the new offices and experiments that followed from it.