AskDefine | Define caltrop

Dictionary Definition



1 tropical annual procumbent poisonous subshrub having fruit that splits into five spiny nutlets; serious pasture weed [syn: devil's weed, Tribulus terestris]
2 a plant of the genus Trapa bearing spiny four-pronged edible nutlike fruits [syn: water chestnut, water chestnut plant]
3 Mediterranean annual or biennial herb having pinkish to purple flowers surrounded by spine-tipped scales; naturalized in America [syn: star-thistle, Centauria calcitrapa]

User Contributed Dictionary



  • qualifier US , /ˈkæltrəp/, /"k

Extensive Definition

A caltrop (calthrop, jack rock, star nail, crow's foot or partisan nails) is a weapon made up of two (or 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). Caltrops serve to slow down the advance of horses, war elephants, and human troops. It was said to be particularly effective against the soft feet of camels. In more modern times, caltrops are used against wheeled vehicles with pneumatic tires. In Japan such devices were known as makibishi.
The device shares its name with the caltrop, Tribulus terrestris (Zygophyllaceae), whose spiked seed case can also injure feet and puncture tires. It can also be compared to the Star thistle, Centaurea calcitrapa, whose Latin name calcitrapa means "foot trap".


Iron caltrop were used as early as 331 BC at Gaugamela according to Quintus Curtius (IV.13.36). They were known to the Romans as tribulus or sometimes as Murex ferreus, the latter meaning 'jagged iron'.
The late Roman writer Vegetius, referring in his work De Re Militari to scythed chariots, wrote:
The armed chariots used in war by Antiochus and Mithridates at first terrified the Romans, but they afterwards made a jest of them. As a chariot of this sort does not always meet with plain and level ground, the least obstruction stops it. And if one of the horses be either killed or wounded, it falls into the enemy's hands. The Roman soldiers">Roman legionRoman 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. A caltrop is a device composed of four spikes or points arranged so that in whatever manner it is thrown on the ground, it rests on three and presents the fourth upright.
This device was used with great success by the Scots against the English at the Battle of Bannockburn in 1314, to disable horsemen. The Drummond clan deployed welded nail caltrops, halting English cavalry in its tracks and saving vital Scots infantry in a battle that meant over 4,000 English troops lost their lives and Edward II had to retreat without shield and sword. Their use undoubtedly contributed to the resounding Scottish victory.
The caltrop continued in use into the 17th century; a single example was found in Jamestown, Virginia in the USA.
Undoubtedly the most unusual weapon or military device surviving from seventeenth-century Virginia is known as a caltrop, a single example of which has been found at Jamestown. It amounts to a widely spread iron tripod about three inches long with another leg sticking vertically upward, so that however you throw it down, one spike always sticks up. ... There is no doubt that the most inscrutable Indian treading on a caltrop would be shocked into noisy comment. ... The fact that only one has been found would seem to suggest that they were used little, if at all. As with all military equipment designed for European wars, the caltrop’s presence in Virginia must be considered in the light of possible attacks by the Spaniards as well as assaults from the Indians.
Punji sticks and caltrops were used in the Vietnam War, sometimes with poison or manure on the points.

Caltrop-like devices

Punji sticks perform a similar role to caltrops. These are sharpened sticks placed vertically in the ground. Their use in modern times targets the body and limbs of a falling victim rather than well shod feet, by means of a pit or tripwire.
In Britain, 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. Very much more common were concrete devices called dragon's teeth that were designed to wedge into tank treads. However, dragon's teeth are immobile, so the analogy with the caltrop is inexact. Another caltrop-like WWII defence is the massive, steel, freestanding Czech hedgehogs that were designed as anti-tank obstacles and were also used to damage ships and landing craft.
The caltrop is the symbol of the US Army's III Corps, which is based at Fort Hood, Texas. III Corps traces its lineage to the days of horse cavalry, which used the caltrop as an area denial weapon. Fort Hood is the only installation in the US Army that has declared the caltrop to be a weapon prohibited in the barracks.

Modern uses

Tire Deflation Device

There have been a number of attempts to develop a caltrop like device that will deflate tires in a manner useful to law enforcement agencies or the military.

Australian Light Horse troops

Caltrops were collected by Australian Light Horse troops as keepsakes. These Caltrops were either made by welding two pieces of wire together to form a four pointed star or pouring molten steel into a mould to form a solid, seven pointed star. The purpose of these devices was to disable horses. They were exchanged with French troops for bullets. The Australian Light Horse troops referred to them as "Horse Chestnuts". Examples from 1917 are kept in the Cart Museum in Bundeena, situated in the state of Victoria, Australia.

Labor activists

Caltrops have been used at times during labor strikes and other disputes. Such devices were used by some to destroy the tires of management and replacement workers.
Because of the prevalence of caltrops during the Caterpillar strike of the mid-1990s, the state of Illinois passed a law making the possession of such devices a misdemeanor.

Environmental activists

In the 1970s, activists in the United States deployed caltrops against the tires of logging trucks. Earth First! quickly condemned the practice, seeing it as a hazard to humans and animals.

See also



  • Clan Drummond. A brief summary of the clan's history.
  • New Discoveries at Jamestown, Site of the First Successful English Settlement in America By John L. Cotter and J. Paul Hudson 1957 Project Gutenberg.
caltrop in Danish: Partisansøm
caltrop in German: Krähenfuß
caltrop in Spanish: Abrojo (arma)
caltrop in Korean: 마름쇠
caltrop in Latin: Murex ferreus
caltrop in Dutch: Voetangel
caltrop in Serbian: Чичак (оружје)
caltrop in Swedish: Fotangel
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