Chinju-fu (in ancient times) (鎮守府 (古代))

Chinju-fu is an office in charge of military affairs in ancient Japan, located in Mutsu Province. As the word "shogun," its commander-in-chief, was first mentioned in 729, it is assumed that an institution equivalent to the Chinju-fu was established in some area in Togoku (the eastern part of Japan, particularly the Kanto region) in the early Nara period. The job grade of Chinju-fu shogun, Commander-in-chief, was equivalent to goi (Fifth Rank) or shii (Fourth Rank).

It is generally assumed that the predecessor of Chinju-fu was Chinjo (Pacification headquarters) mentioned in Shoku Nihongi (Chronicle of Japan Continued), which was attached to Taga-jo Castle where Mutsu kokufu (the provincial capital of Mutsu province) is supposed to have been located. Later, in 802, SAKANOUE no Tamuramaro built Isawa-jo Castle, and then Chinju-fu was moved to Isawa-jo Castle.

Taga-jo Castle Period

It is assumed that an institution equivalent to the Chinju-fu was first established in Taga-jo Castle.

In 759, it was decided that payment of remuneration and provision of servants for the shogun and for his subordinate officers should be the same as those for Kokushi (provincial governor) of Mutsu Province. Around this time, the Chinju-fu shogun started to be appointed around every four years. In those days, the shogun generally doubled as Azechi (inspector of the provincial government) or as Mutsu no kami (the governor of Mutsu Province), and some even held three positions at once.

For expeditions to fight barbarians, Seii Taishi (great general who subdues the barbarians) or Seito Taishi (great general who subdues the eastern barbarians) was appointed and Seitogun (expeditionary force) was organized under him. The Chinju-fu is said to have been in charge of military affairs in Mutsu Province, including ordinary defense and the construction and maintenance of josaku (official defense site).

Isawa-jo Castle Period

In 802, when SAKANOUE no Tamuramaro built Isawa-jo Castle, Chinju-fu was relocated from Taga-jo Castle to Isawa-jo Castle. After this relocation the institutional structure was proactively organized and, for example, in 812, the number of officials composing Chinju-fu was clearly specified; one shogun, one gungen (assistant deputy general), two sergeants, one doctor and one do-shi (commissioned officer of big bow).

The official seal of Mutsu Province had been used in the Chinju-fu but in 834 an official seal of the Chinju-fu was created and supplied. Thus the Chinju-fu after the relocation served as a second kokufu, which operated separately from the Mutsu kokufu located in Taga-jo Castle, and controlled Isawa (south of Iwate Prefecture).

Thus the Chinju-fu was originally designed to serve as a peacetime governing institution, not to subdue barbarians in emergencies. So after the mid Heian period the true function of the Chinju-fu was forgotten and only the title of Chinju-fu shogun remained, being granted as military glory.