THE SPECIAL FORCE OF THEN

Black-clad figures with muffled faces skitter through a courtyard, swarming over walls like spiders and running lightly across rooftops, quick as cats.
An unsuspecting samurai sleeps peacefully as these shadows permanently silence his bodyguards. The bedroom door slides open without a sound, an upraised blade glints in the moonlight, and...
This is the ninja of the movies and comic books, the stealthy assassin in black robes with magical abilities in the arts of concealment and murder.

This wraith-like being is very compelling, to be sure. But what is the historical reality behind the popular culture icon of the Ninja?

Origins of the Ninja

It is difficult to pin down the emergence of the first ninja, more properly called shinobi — after all, people around the world have always used spies and assassins. Japanese folklore states that the ninja descended from a demon that was half man and half crow. However, it seems more likely that the ninja slowly evolved as an opposing force to their upper-class contemporaries, the samurai, in early feudal Japan.
Most sources indicate that the skills that became ninjutsu, the ninja's art of stealth, began to develop between 600 to 900 and Prince Shotoku, who lived from 574 to 622) is said to have employed Otomono Sahito as a shinobi spy.
By the year 907, the Tang Dynasty in China fell, plunging the country into 50 years of chaos and forcing Tang generals to escape over the sea to Japan where they brought new battle tactics and philosophies of war.

Chinese monks also began to arrive in Japan in the 1020s, bringing new medicines and fighting philosophies of their own, with many of the ideas originating in India and making their way across Tibet and China before turning up in Japan. The monks taught their methods to Japan's warrior-monks, or yamabushi, as well as to members of the first ninja clans.

The First Known Ninja School

For a century or more, the blend of Chinese and native tactics that would become ninjutsu developed as a counter-culture, without rules, but it was first formalized by Daisuke Togakure and Kain Doshi around the 12th century.
Daisuke had been a samurai, but he was on the losing side in a regional battle and forced to forfeit his lands and his samurai title. Ordinarily, a samurai might commit seppuku under these circumstances, but Daisuke did not.
Instead, in 1162, Daisuke wandered the mountains of southwest Honshu where he met Kain Doshi, a Chinese warrior-monk — Daisuke renounced his bushido code, and together the two developed a new theory of guerrilla warfare called ninjutsu. Daisuke's descendants created the first ninja ryu, or school, the Togakureryu.

Who Were the Ninja?

Some of the ninja leaders, or jonin, were disgraced samurai like Daisuke Togakure that had lost in battle or had been renounced by their daimyo, but fled rather than committing ritual suicide. However, most ordinary ninjas were not from the nobility.
Instead, low-ranking ninjas were villagers and farmers who learned to fight by any means necessary for their own self-preservation, including the use of stealth and poison to carry out assassinations.

As a result, the most famous ninja strongholds were the Iga and Koga Provinces, mostly known for their rural farmlands and quiet villages.

Women also served in ninja combat. Female ninja, or kunoichi, infiltrated enemy castles in the guise of dancers, concubines or servants who were highly successful spies and sometimes even acted as assassins as well.

Samurai Use of the Ninja

The samurai lords could not always prevail in open warfare, but they were constrained by bushido, so they often hired ninjas to do their dirty work — secrets could be spied out, opponents assassinated, or misinformation planted, all without sullying a samurai's honor.
This system also transferred wealth to the lower classes, as the ninja were paid handsomely for their work. Of course, a samurai's enemies could also hire ninja, and as a result, the samurai needed, despised, and feared the ninja — in equal measure.
The ninja "high man," or jonin, gave orders to the chunin, "middle man," who passed them on to the genin, or the ordinary ninja. This hierarchy was also, unfortunately, based on the class the ninja had come from before training, but it wasn't uncommon for a skilled ninja to ascend the ranks well beyond his or her social class.

The Rise and Fall of the Ninja

The ninja came into their own during the tumultuous era between 1336 and 1600, where an atmosphere of constant war, ninja skills were essential for all sides, playing a key role in the Nanbukucho Wars (1336 - 1392), the Onin War (1460s), and even through the Sengoku Jidai, or "Warring States Period" — where they aided samurai in their internal power struggles.
The ninja were also an important tool during the Sengoku Period (1467 - 1568) but also a destabilizing influence. When war-lord Oda Nobunaga emerged as the strongest daimyo and began to reunite Japan in 1551 to 1582, he saw the ninja strongholds at Iga and Koga as a threat, but despite quickly defeating and co-opting the Koga ninja forces, Nobunaga had more trouble with Iga.
In what would later be called the "Iga Revolt" or Iga No Run, Nobunaga attacked the ninja of Iga with an overwhelming force of more than 40,000 men. Nobunaga's lightning-quick attack on Iga forced the ninja to fight open battles, and as a result, they were defeated and scattered to nearby provinces or the mountains of Kii.
While their power-base was destroyed, the ninja did not vanish entirely. Some went into the service of Tokugawa Ieyasu, who later became shogun in 1603, but the much-reduced ninja continued to serve both sides in struggles. In one famous incident from 1600, a ninja sneaked through a group of Tokugawa's defenders at Hataya castle and planted the flag of the besieging army high on the front gate!
The Edo Period under the Tokugawa Shogunate from 1603 to 1868 brought stability and peace to Japan, bringing the ninja story to a close. Ninja skills and legends survived, though, and were embellished to enliven the movies, games and comic books of today.