Kempo

Overview

Kempo (建保) was a Japanese era name (年号, nengō; literally "year name") that followed the Kenryaku era and preceded the Jōkyū era. The era spanned from December 1213 through April 1219, during the Kamakura period (1185–1333). The reigning emperor during this time was Emperor Juntoku (順徳天皇).

Era names in Japan mark years by imperial decree, resetting the calendar count at the start of each new era. The Kempo era lasted roughly five and a half years, a relatively short span within the broader Kamakura period.

What Defined the Era

The Kempo era unfolded during a time when political power was divided between the imperial court in Kyoto and the shogunate in Kamakura. The Kamakura shogunate, established in 1185, had consolidated its authority under the Hōjō clan, who served as regents to the shogun. By 1213, the shogunate was firmly in control of military affairs, while the imperial court retained ceremonial and some administrative functions.

Emperor Juntoku, who reigned from 1210 to 1221, occupied the throne throughout the Kempo era. His reign would later be defined by the Jōkyū War of 1221, in which he and his father, the retired Emperor Go-Toba, attempted to overthrow the shogunate. The seeds of that conflict were already present during the Kempo years, as the imperial court chafed under shogunal dominance.

The era name itself was chosen to signal a new beginning. The character 建 (ken) carries the sense of "establishing" or "founding," while 保 (po) means "protecting" or "preserving." Together, the name suggests a period of establishing and safeguarding peace, a common aspiration for era names of the time.

Key Events

The Kempo era saw the continued consolidation of Hōjō power within the shogunate. In 1213, the same year the era began, the Hōjō regent Hōjō Yoshitoki crushed the Wada clan, a rival military house, in a decisive confrontation. This victory eliminated a major threat to Hōjō supremacy and solidified the regent's control over the shogunate's military apparatus.

In 1215, the shogunate issued a series of legal pronouncements aimed at regulating the conduct of warriors and settling land disputes. These measures reinforced the shogunate's judicial authority and extended its reach into the provinces. The Kamakura government was becoming not just a military power but an administrative one, with its own courts and legal precedents.

The Kempo era also witnessed the continued construction and maintenance of temples and shrines, a traditional duty of the imperial court. Emperor Juntoku engaged in these religious and cultural activities, which served to affirm the court's legitimacy even as its political power waned. The era was not marked by major wars or natural disasters, but rather by the quiet consolidation of shogunal rule.

In 1219, the era came to an end when the shogunate and the court agreed to change the era name, likely to mark a new phase in the imperial calendar. The Jōkyū era that followed would prove far more turbulent, culminating in the Jōkyū War of 1221.

The Name in Japanese

The era name is written 建保 in kanji.

• Kana reading: けんぽう
• Romaji: Kenpō (also romanised as Kempo)

The name consists of two kanji characters:

• 建 (ken) — reading in this word: けん. This character means "to build," "to establish," or "to found." It appears in words like 建設 (kensetsu, "construction") and 建国 (kenkoku, "founding of a nation"). In the context of an era name, it conveys the idea of establishing something new, such as a period of peace or a new political order.

• 保 (po) — reading in this word: ぽ. This character means "to protect," "to preserve," or "to maintain." It appears in words like 保護 (hogo, "protection") and 保険 (hoken, "insurance"). In the era name, it suggests safeguarding what has been established, whether that be peace, stability, or the realm itself.

When combined, 建保 carries the sense of "establishing and protecting" — a wish for a period in which the foundations of governance are laid and then preserved. The reading けんぽう follows the standard on-yomi (Chinese-derived reading) for both characters, with the second character's initial consonant becoming voiced (po instead of ho) due to a phonological process called rendaku, or sequential voicing, which commonly occurs in Japanese compound words.

How the Era Name Works

The Japanese era name system, known as nengō (年号), dates back to 645 CE, when the first era name, Taika, was proclaimed. The system was modelled on Chinese practice and served to mark time by imperial reign, with each era name reflecting the aspirations or circumstances of its time.

An era name is proclaimed by the emperor, typically on the advice of court scholars and officials. The name is chosen from classical Chinese texts and is meant to convey an auspicious meaning. Era names are not tied to the emperor's reign alone; a single emperor might see several era changes during his time on the throne, as was the case with Emperor Juntoku, who reigned through three different eras.

The era name changes for various reasons: the accession of a new emperor, the beginning of a new sexagenary cycle, a natural disaster, or a significant political event. The change from Kenryaku to Kempo in December 1213 was likely prompted by such a combination of circumstances, though the specific reason is not recorded in the surviving sources.

For students of Japanese, era names are more than historical curiosities. They appear in official documents, on gravestones, and in historical records. Knowing the era name helps place events in time, and the names themselves offer a window into the values and concerns of the period. The Kempo era, with its emphasis on establishing and protecting, reflects the priorities of a shogunate that was still consolidating its power and a court that sought stability in uncertain times.