Caltrop

A caltrop (also known as caltrap, galtrop, cheval trap, galthrap,[1] galtrap, calthrop, jackrock or crow's foot[2][3]) is an area denial weapon made up of usually four, but possibly more, sharp nails or spines arranged in such a manner that one of them always points upward from a stable base (for example, a tetrahedron).

Historically, caltrops were part of defences that served to slow the advance of troops, especially horses, chariots, and war elephants, and were particularly effective against the soft feet of camels.

The Roman soldiers rendered them useless chiefly by the following contrivance: at the instant the engagement began, they strewed the field of battle with caltrops, and the horses that drew the chariots, running full speed on them, were infallibly destroyed.

Both types of makibishi could penetrate the thin soles of shoes, such as the waraji sandals, which were commonly worn in feudal Japan.

[16][17] Inventors patented caltrop-like devices to deflate vehicle tires in a manner useful to law enforcement agencies or the military.

Caltrops, referred to as "jack rocks" in news articles, were used during the Caterpillar strike in 1995, puncturing tires on vehicles crossing the picket line in Peoria, Illinois.

[citation needed] It has also been adopted by military units: the caltrop is the symbol of the US Army's III Corps, which is based at Fort Cavazos, Texas.

III Corps traces its lineage to the days of horse cavalry, which used the caltrop as a defensive area denial weapon.

[citation needed] During the Second World War, large caltrop-shaped objects made from reinforced concrete were used as anti-tank devices, although it seems that these were rare.

Another caltrop-like defence during World War II was the massive steel, freestanding Czech hedgehog; the works were designed as anti-tank obstacles and could also damage landing craft and warships that came too close to shore.

[25] Czech hedgehogs are heavily featured and plainly visible in the 1998 Steven Spielberg-directed American epic war film Saving Private Ryan, throughout the scenes early in the film depicting the June 6, 1944 Omaha Beach assault (part of the Normandy landings during World War II).

They are used as riprap in the construction of breakwaters and other sea defences, as they have been found to let the water pass through them and interrupt natural processes less than some other defenses.

Roman caltrop at the Westphalian Museum of Archeology (German: Westfälisches Museum für Archäologie), Herne, North Rhine-Westphalia , Germany
Different types of caltrops and metal soles that can be buckled underneath as a countermeasure from Codex Löffelholz, Nuremberg, 1505
Bronze caltrops from the Three Kingdoms era
A 16th-century caltrop
Illustration from the 18th-century Chinese book Gujin Tushu Jicheng , showing caltrops with spikes that stick in the ground
Crow's feet boards studded with spikes. These were laid on the ground to prevent the enemy from approaching the defences. This board was used by the Russian Army during the Battle of Balaclava . On display at Royal Engineers Museum, Kent.
Caltrop used by the US Office of Strategic Services . The hollow spikes puncture self-sealing rubber tires. The hole in the center allows air to escape even if other ends of the tube are sealed by soft ground.
Czech hedgehogs deployed at the Stachelberg fortress in Czechoslovakia in 1938