Tetsubishi are nasty little tools that a shinobi-no-mono would use to puncture the feet of his pursuers. In those days, these testubushi were made from bamboo or iron and carried on person as an aid to infiltration missions and emergency egress situations. It is documented within the Bansenshukai that, before stealing into a building, tetsubishi would be dropped around the entrances for assurance if something were to go wrong and the shinobi found himself being given chase by barefooted or sandaled warriors, these little traps would surely hamper his pursuers.
In the west we refer to these miniature weapons as “caltrops” from the latin ‘calcitrapa’ which literally translates as ‘foot-trap’, and armies since time memorial have utilized them with the same principle of shinobi-no-jutsu in mind – attack the means to pursue. Alexander the Great employed them, and even the Office of Strategic Services (OSS), the forerunner to the CIA, is said to have used them:
“During World War II, caltrops were used extensively for Jedburgh team operations. The Jedburgh teams were created in the early days of the Office of Strategic Services—the predecessor of today’s CIA. The teams of American, British and French officers would parachute into enemy-occupied territory to conduct sabotage. The Jedburghs scattered caltrops across enemy aircraft runways. These caltrops were made out of hollow spikes, which could puncture a self-sealing tire and cause it to blow out. When a fighter plane rolled over a caltrop during take off or landing, the tires would blow out, causing the plane to go into an uncontrollable ground loop and eventually crash.”
Tetsubishi have since then been used in a litany of geographical regions for defense purposes, and now an example will be given of how you can use this principle in creating implements of home-defense.
Say you have an acreage; or you are a preparedness advocate; or you simply like medieval style weapons; whatever the case may be, tetsubishi like devices will probably be able to aid you in deterring home invaders, trespassers, and hordes of zombies (ok, maybe not that last one, but you get the idea).
Spike-boards can be deployed beneath windows, outside or inside entrances, or along roads and even foot-paths. All that is really required are some nails or screws and wood. As shown below, you can even go so far as to have the boards painted and camouflaged by natural foliage. Specific uses are determined by the user’s circumstances. Disclaimer: This is for informational purposes only.