• Locals: Recruited from the enemy’s general population.
• Insiders: Disaffected officials from the government of the enemy state, including relatives of persecuted officials (think John Walker Jr. and family). The treatise elaborates on ways to identify ‘inside spies’ from a host of situations, and whom to approach: the ambitious, the dejected, the suppressed, the punished, and the duplicitous.
• Double agents: Enemy agents who have been turned (with bribes, promises, ideals, etc.), who are willing to spy against their old master or send back false information.
• Expendables or Canary: Dispensable agents who are fed false information by the general. This false information is eventually found out and the spy is executed by the enemy.
• Indispensables: These are the alpha spies—iron-willed but simple in appearance, they never let their guard down and operate effectively in enemy territory. They are allegedly immune to betrayal and seduction but practice it on others with ease.

The Mongols under Genghis Khan used spies to further their military and political operations, too, often with a much greater degree of ruthlessness. Prior to any military campaign, the Mongols carefully scouted out and spied on their enemies. Prior to the invasion of Europe, Batu (grandson of Genghis Khan) and Subutai (field commander) sent spies for almost 10 years into the heart of Europe, making maps of the old Roman roads, establishing trade routes, and determining the level of ability of each area to resist invasion.

They made tactical and strategic decisions based on reconnaissance and spies regarding the willingness of each city to aid the others, and their ability to resist alone or together. Also, when invading an area, the Mongols would do all that was necessary to completely conquer the town or cities.

When thinking of spying and espionage in ancient Asia, probably the most famous group that comes to mind are the Japanese ninja or shinobi (“to steal away”). The first written records of the ninja appeared in about the 15th and 16th centuries (the Sengoku, or “warring states,” Period), but some variation of the group is said to have existed in the 14th and perhaps even 12th centuries.

Probably the best description of the ninja was that of a mercenary, and their duties included espionage, sabotage, infiltration, assassination, and even open combat on rare occasions. It should be noted that there also existed dedicated “other-than-ninja” organizations, such as the Edo-Period secret police, some of which were initiated and commanded by Sengoku Jidai “veterans” who had commando/ninja/spy experience. Think of the ninja as the DIA (Defense Intelligence Agency) to the secret police’s more CIA (Central Intelligence Agency)-like role.

It is believed that basic ninja concepts were drawn from Chinese military philosophy, with the most popular written manual being the Bansenshukai, written about 1676. Within each manual were multiple volumes touching on such topics as leadership and philosophy, with a total of eight volumes devoted to the use of spies and espionage: three volumes on “open disguise” or yo-nin, and five volumes on “hidden infiltration,” or in-nin. The training taught in these manuals, combined with the ninja’s expert use of stealth and covert tradecraft, made for many tall tales and stories of their ability to render themselves invisible, walk on water, and even breathe fire.

Most experts believe that it was around the 15th century that the ninja began to be employed as spies. Political and military unrest comprised the atmosphere of the day, and leaders realized that, in stark contrast to the code of conduct and strict ritual of the samurai, they needed a group of men (and women, called kunoichi) who were willing to perform acts deemed not respectable to conventional warriors.

They turned to the two families most prominent in this expertise, the Iga and Koga clans, hiring them in secret to conduct missions ranging from espionage to assassinations. The clans employed a system of rank, where the jonin (“upper man”) was the highest rank, representing the group and hiring out mercenaries. Next were the chunin (“middle man”), assistants to the jonin. At the bottom was the genin (“lower man”), field agents drawn from the lower class, and assigned to carry out actual missions.

In the end, and despite what Hollywood portrays, espionage was the chief role of the ninja, and contrary to popular belief, the depiction of ninja versus samurai has been found to be largely false. In fact, it has been discovered many of the more “famous” ninjas, including the big man, Hotori Honzo, were dual-hatted as samurai.

Almost every Koryu traditional Japanese martial arts school that predates the Edo Period has shinobi (ninja) curriculum included. Students were taught, among other things, the use of disguises, how to surreptitiously gather information on enemy terrain and structure specifications, and steal passwords and communications. A supplement to the Nochi Kagami, a record of the Ashikaga shogunate, briefly describes the ninja’s role in espionage:

“Concerning ninja, they were said to be from Iga and Kōga, and went freely into enemy castles in secret. They observed hidden things, and were taken as being friends.”

Later in history, the Kōga ninja would become regarded as agents of the Tokugawa shogunate, at a time when the ninjas were utilized as an intelligence network to monitor regional daimyos (lords) as well as the imperial court.

This article was originally published in 2014.