Caltrop A caltrop ( also known as caltrap , galtrop , cheval trap , galthrap , galtrap , calthrop , crow ' s foot ) is an antipersonnel 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 were part of defenses that served to slow the advance of horses , war elephant s , and human troops . They were said to be particularly effective against the soft feet of camels . In more modern times , caltrops are used against wheeled vehicles with pneumatic tire s . The modern name " caltrop " is derived from the Latin " calcitrapa " ( foot - trap ) . The synonymous Latin word " tribulus " gave rise to the modern Latin name of a plant offering similar hazards to sandaled or bare feet , " Tribulus terrestris " ( Zygophyllaceae ) , whose spiked seed case can injure feet and puncture tires . This plant can also be compared to the starthistle , " Centaurea calcitrapa " , which is sometimes called the " caltrop " . A water plant with similarly - shaped spiked seeds is called the " water caltrop " , " Trapa natans " . History . According to Quintus Curtius ( IV . 13 . 36 ) , iron caltrops were used as early as 331 BC at Gaugamela . They were known to the Romans as " tribulus " or sometimes as " murex ferreus " , the latter meaning ' jagged iron ' . They were used in the Battle of Carrhae in 51 BC . The late Roman writer Vegetius , referring in his work " De Re Militari " to scythed chariot s , wrote : Contrary to popular belief , there is no evidence that the caltrop was used in either the first Wars of Scottish Independence ( 1296 – 1328 ) , or second wars ( 1332 – 1357 ) . A single example was found in Jamestown , Virginia , in the United States . The Japanese version of the caltrop is called makibishi . " Makibishi " were sharp spiked objects that were used in feudal Japan to slow pursuers and also were used in the defence of samurai fortifications . Iron " makibishi " were called " tetsubishi , " while the " makibishi " made from the dried seed pod of the water chestnut , formed a natural type of " makibashi " called " tennenbishi " . Both types of " makibishi " could penetrate the thin soles of shoes , such as the waraji sandals , that were commonly worn in feudal Japan . Caltrops were used extensively and to very good effect during World War II . The modifications and variants produced by the Special Operations Executive ( SOE ) and the Office of Strategic Services ( OSS ) of the United States are still in use today within Special Forces and Law Enforcement bodies . Caltrop - like devices . Punji stick s 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 by means of a pit or tripwire . 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 . Much more common were concrete devices called dragon ' s teeth , which were designed to wedge into tank treads . Large ones weighing over are still used defensively by the army to deny access to wheeled vehicles , especially in camp areas . As dragon ' s teeth are immobile , the analogy with the caltrop is inexact . 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 warship s that came too close to shore . These were used by the Germans to defend beaches at Normandy and other coastal areas . Tetrapods are concrete blocks shaped like caltrops , which interlock when piled up . They are used 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 . Modern uses . Tire deflation device . Researchers have tried to develop a caltrop - like device to deflate vehicle tires in a manner useful to law enforcement agencies or the military . Australian Light Horse troops . During service in World War I , Australian Light Horse troops collected caltrops 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 , in the state of Victoria , Australia . Labor activists . Caltrops have been used at times during labor strike s and other disputes . Such devices were used by some to destroy the tires of management and replacement workers . In this context , caltrops are usually referred to as " jack rocks . " They have become icons at pro - union rallies , often depicted on t - shirts , hats , or worn as jewelry in some cases . Because of labor ' s use of caltrops during the Caterpillar strike of the mid - 1990s in Illinois , the state legislature passed a law making the possession of such devices a misdemeanor . Symbolic use . A caltrop has had a variety of symbolic uses and is commonly found in heraldry . for instance , the Finnish noble family Fotangel ( Swedish for ' caltrop ' ) had arms " Gules , three caltrops Argent " . It has been adopted by military units : 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 a defensive area denial weapon . It is also the symbol of the United States Marine Corps ' 3rd Division , formed on September 16 , 1942 .