The Czech Hedgehog was an anti-tank fortification that was used extensively during WWII by several countries. They were called hedgehogs for their spiky appearance and they were constructed mainly of steel. Although, steel could be swapped out for any metal that can withstand the forces of combat such as explosions, bullets, etc. The standard amount of force a hedgehog can take is often 60,000 kg. In order to attain maximum effectiveness, hedgehogs are made to a height of about 1.1 meters.
Hedgehogs are very effective at stopping tanks,especially if there are several hedgehogs crammed into narrow streets. Just like rubble, it makes the streets near impassable. Hedgehogs work by having a tank trying to push it out of the way and having the hedgehog roll under the tank so that it lifts the tank treads off the ground, therefore disabling it until the crew can properly destroy the hedgehog, in which time they maybe ambushed or captured.
Still, this means there must be infantry or machine guns positioned nearby to cover the line. In order to disable tanks, hedgehogs must be placed in one or two straight rows, no more are needed and additional fortifications will not allow the other hedgehogs to function properly. Hedgehogs have an advantage over other fortifications in that they can be moved if it is required unlike Dragon's Teeth which are stationary.
The Czech Hedgehog, as the name implies was first developed in Czechoslovakia and was placed in the Czechoslovak Border Fortifications (1935-1938). The design was quickly adopted by Germany and in 1941, the Soviet Union used hedgehogs heavily to stop the German tank onslaught. One of the most famous uses of the hedgehog was in the Atlantic Wall in Normandy, France. During the Normandy Breakout, some allied tanks even strapped modified hedgehogs to the front of their vehicles to cut through the thick hedgerows making up a substantial portion of the French Bocage countryside.