The One Province, One Castle Order (1615)

Overview

The One Province, One Castle order (Ikkoku Ikkojo-rei) was a law issued by the Edo shogunate on the thirteenth day of the intercalary sixth month of Keicho 20 (7 August 1615). It ordered each daimyo to keep a single castle as a residence or seat of government and to dismantle all the others. The issuing authority was the second shogun, Tokugawa Hidetada, with Doi Toshikatsu, Ando Shigenobu and Sakai Tadayo countersigning, and the plan is attributed to the retired shogun Tokugawa Ieyasu. Some sources and dictionaries give the sixth month for its issue, so the date varies by source; here the widely cited thirteenth day of the intercalary sixth month is used.

Background

The immediate background was the fall of the Toyotomi in the Summer Siege of Osaka (May 1615). The remaining task for the shogunate was to restrain the military power of the daimyo, especially the tozama (outer) daimyo of western Japan. The aim included preventing wars between daimyo as well as rebellion against the shogunate.

From the Sengoku into the Azuchi-Momoyama period, castles large and small were built everywhere, and it is said that there were close to 3,000 across Japan. Many were military bases of local lords, and reducing their number was an effective way to narrow the bases of armed force.

Content and application

The principle of the order was that a daimyo would keep one castle for use as a residence and dismantle the rest. The word "province" had two senses: the ancient provinces and the daimyo's domain. Where several daimyo divided one province, each was allowed one castle; where one daimyo house spanned several provinces, one castle per province was allowed. In Iyo, for example, Ozu, Matsuyama and Uwajima castles remained as the seats of different daimyo, while the Todo house kept Anotsu Castle in Ise and Ueno Castle in Iga.

Application was not uniform, however. In large domains, kinsmen or retainers sometimes held what were in effect castles, as was often seen among daimyo of the Oshu and Hokuriku regions. The Maeda kept two castles in Kaga, Kanazawa and Komatsu; the Ikeda of Tottori kept three in Inaba and Hoki; the Kii Tokugawa kept five; and the Hosokawa kept two, Kumamoto and Mugishima (later Yatsushiro).

Course of events

Once the order was issued, the daimyo pulled down their castles other than their seats. About 400 castles are said to have been razed within a few days. The Mori kept Hagi Castle and demolished Iwakuni and others; the Nabeshima demolished everything but Saga Castle; the Kuroda demolished all six satellite forts except Fukuoka Castle; and the Yamauchi demolished everything but Kochi Castle. The Ii demolished the castles of Omi other than Hikone; the Owari Tokugawa kept only Nagoya Castle and demolished others including Kiyosu; and the Horio demolished the castles of Izumo and Oki other than Matsue. The Matsura had already demolished Hirado and Katsumoto castles before the order.

The Ikoma reported that they had destroyed everything but Takamatsu Castle, but it was later discovered that Marugame Castle had in fact not been demolished. This is one example of the variety of local circumstances and responses in carrying out the order.

Connection to swords and castles

For castles the effect was decisive. The close to 3,000 castles said to have existed in the Azuchi-Momoyama period fell to about 170, or about 300 if jinya (administrative residences) are counted. Many of the castles whose keeps and stone walls survive today descend from those that were left standing then.

Retainers and townspeople gathered to live in the castle towns of the surviving castles. With samurai concentrated in castle towns, the paired long and short swords that marked samurai status came to be seen as symbols of rank in the everyday scenery of those towns. The order itself did not directly regulate swords; its effect on them was only indirect, through the reduction of military bases and the move of samurai life to the castle towns.

Impact

The Buke Shohatto, promulgated in the seventh month of the same year, are reported to have required repairs of castles to be reported and new construction to be prohibited, and together with the One Province, One Castle order they institutionalized the control of castles. It became difficult for daimyo to build castles freely and increase their military bases. The effect of strengthening Tokugawa control of the country is said to have been applied most thoroughly in western Japan, where many tozama daimyo lived.

Implementation was not uniform, though; each domain adapted by controlling branch families, through transfers of fief, and according to local conditions. The number of castles fell greatly, but there was still some room beyond shogunal control.

Assessment and legacy

The order is regarded as having settled the end of the Sengoku period in institutional terms. In the shift of castles from military bases to administrative centers, the castles left standing became the core of later castle-town development.

Today, both the castles whose keeps survive as National Treasures or Important Cultural Properties and the ruins where only stone walls remain can be seen as legacies of the landscape this order created. Swords and castles are both emblems of samurai culture, and knowing this order helps in understanding the setting of samurai life.