Czech hedgehog

The hedgehog is very effective in keeping light to medium tanks and vehicles from penetrating a line of defense; it maintains its function even when tipped over by a nearby explosion.

During the invasion of Normandy, the Allies cut up sizable numbers of intact and wrecked hedgehogs and welded them to the front of their M4 Sherman and M5 Stuart tanks.

Postwar tests conducted by the Czechoslovak army proved the low efficiency of the metal hedgehogs against heavy armored vehicles such as the Soviet ISU-152 and T-54 or German Panther.

As many as 40% of attempts at breakthrough were successful; therefore, the army developed new anti-tank obstacles for the border fortifications instituted during the Cold War.

Its effectiveness lies in its dimensions, combined with the fact that a vehicle attempting to drive over it will likely become stuck (and possibly damaged) through rolling on top of the lower bar and lifting its treads (or wheels) off the ground.

[11] Industrially manufactured Czech hedgehogs were made of three pieces of metal angle (L 140/140/13 mm, length 1.8 metres (6 ft), weight 198 kilograms (440 lb); later versions: length 2.1 metres (7 ft), weight 240 kilograms (530 lb) joined by gusset plates, rivets and bolts, or welded together into a characteristic spatial three-armed cross with each bar at right angles to the other two, this pattern forming the axes of an octahedron.