"The Samurai Powers in the Kinai (Capital Region) and Iga" (summary)
Lecturer: NAKAGAWA Takaaki
Though it is an unquestionable fact that during the Warring State period, the Iga tribe already had a reputation as a reliable mercenary-type army among the samurai powers in the Kinai (Kyoto-Osaka region), both their difference from other armies and their true nature remain unclear. For that reason, this report attempts to analyze the reality of their rampant within the countries of the Kinai area.
The first step of the analysis is to outline the power structure of the Iga Province during the Muromach and the Warring State periods, which gave birth to the mysterious tribe of Iga, and to investigate the province from the architectural aspect of castles. It became clear that conditions of these castle architectures (i.e., distribution and planar configuration) reflected the power structure of the area.
The investigation continued on to the issues on the combat strategy of the Iga tribe for besieging castles. It elucidating their utilizing of special tactics such as night attack, surprise attack, intrusion and arson attack, to show remarkable achievements in short-term siege (Shirotori, literally 'taking castles'). In fact, they were referred to, and concurrently feared, as "Iga no Shirotori monodomo (the castle-takers of Iga)" by the samurai powers. For example, the record shows that when attacked by the "Iga castle-takers", a samurai lord of the Tanba Province by the name of NAITO Sosho immediately ordered the reinforcement of the guard inside the castle as well as the dispatch of an urgent messenger to his elder brother, MATSUNAGA Hisahide. Especially, the former order specifically stresses that, "it is extremely important to check each personnel, even servants, who go in and out of the castle". It seems that one of the Iga tribe's usual measures was to disguise themselves as the people who frequent in and out of the castle to intrude into the castle. This is a precious example that indicates not only the recognition and preparation of the samurai against the Iga tribe, but also the tactics the tribe used.
"Shirotori" is undoubtedly a keyword when examining the Iga tribe, for it is more than just a term used to understand them by the samurai power. The 5th article of the Iga Sokoku Ikki Okitegaki, literally meaning "Rules for the Province-wide Uprising of Iga) cites the examples of the members of the tribe accomplishing "Shirotori" in other provinces. It also encourages the entire members of the tribe, including even the lower class peasants to participate in taking castles in case of other province's army invading their land.
It indicates that "Shirotori" was considered as the main strategy for the entire province. The fact that there was such a basic value shared by the entire province is not something that can be overlooked.
Thus, according to the examination above, the reality of the Iga tribe was not just a simple mercenary-type army, but more of a group of specialists in castle sieging. Their actions such as the night attacks, which were later regarded as their ninja-esque factors, were actually special skills utilized to eliminate enemies, or namely, to execute "Shirotori". The existence of the Iga tribe with this special skill is possibly one of the roots for the formation of the common images of "Igamono" or "ninja" in modern times.