Japan’s last feudal military government was the Tokugawa Shogunate, where in the head of the government was known as the Shogun. In order to protect the Shogun from potential assassins, this is what they did.
Many people may not have heard about the great place built by Tokugawa Ieyasu, the founder and pioneer of the Tokugawa Shogunate in Japan, naming the palace Nijo-jo in Kyoto. Tokugawa Shogunate that was the last feudal military government in Japan that lived centuries, have an excellent security system in place to protect their Shogun (head of the government).
The power exerted by the Shogun was immense and thus, his enemies back then were also very powerful. This was the reason why Tokugawa installed the finest security system in his palace to protect it from potential assassins, by orchestrating the era’s state of the art system: which is a floor that announces intruders as well as modern alarm!
Yes, you heard that right. A floor that announces the intruders!
The prime concern for the Nijo-Jo was not a ninja attack on them, but the fear of thieves.
The nightingale floor was the most secured floor in the palace and their code of weapon was silence.
Silence was chosen by the protectors because if an intruder enters the floor, irrespective of how much careful he is, he is expected to make a low pitch sound like a chirp or a whistle. How is this sound generated? The sound is caused due to the metal flooring. The pressure of a footstep causing the nails throughout the surface of the floor to squeal against their metal jackets. This emits a sound like a birdsong thereby alerting the palace guards.
This feature is there in several temples in Kyoto, Japan.
The people who used to work at the Shogun’s palace like their priests, patrolling guards and other residents were efficiently trained on how to walk particularly across the floor. Their walk, which was in a fixed rhythm emitted a certain kind of birdsong. When assassins and thieves walked on the floors the rhythm produced by them was extremely different, alerting the guards.
This is a highly intelligent method, spread across the whole floor with a wide pressure sensitive alarm that was invented before the electronics in the western world.
Tokugawa Ieyasu had taken the ninjas seriously as there was a stronghold of the ninjas in the vicinity of Nijo-Jo.
Ninjas in that time were hired by lords to spy on others. Ninja’s were not easy to spot as they dressed very simply like a farmer to extract information and they were extremey skilled.
Thus, these systems were built to protect the Shogunate from assassins, thieves and Ninjas, as Tokugawa had a fear of the ninja stronghold located just 65 kilometers away from his palace.
How amazing is that?