The Czech hedgehog was created in Czechoslovakia during the second world war to prevent the German invasion, this artificial obstacle consists of 4 metal slats welded or riveted in an L to add rigidity, the materials used to be in most cases solid metal and in wood to a lesser extent, thus facilitating its construction, finally resulting in a fairly affordable defensive piece.
The Czech hedgehog is nothing more than the continuation of what is known as the "Frisian horse", this element also acted as a barrier consisting of the burying of stones very close together at regular intervals, leaving their sharp or pointed edge, outwards. so that to cross this obstacle it was necessary to dismount in case the soldier was mounted, in many cases it was not surmountable by the army on foot either.
Another historical precedent is considered to be the walls of pikes driven into the ground by their blunt part, protruding the cutting part, which was also effective to neutralize a cavalry attack.
A variant of the Czech hedgehog would be the concrete blocks or pillars that had the same function, which are also widely used throughout the world in breakwaters and breakwaters to break strong waves.