Chevaux-de-frise

The cheval de frise (plural: chevaux de frise [ʃə.vo də fʁiz], "Frisian horses") was a medieval defensive anti-cavalry measure consisting of a portable frame (sometimes just a simple log) covered with many projecting long iron or wooden spikes or spears. They were principally intended as an anti-cavalry obstacle but could also be moved quickly to help block a breach in another barrier. They remained in occasional use until they were replaced by wire obstacles just after the American Civil War. During the Civil War, the Confederates used this type of barrier more often than the Union forces. During World War I, armies used chevaux de frise to temporarily plug gaps in barbed wire. Chevaux de frise of barbed wire were used in jungle fighting on south Pacific islands during World War II.

The term is also applied to defensive works comprising a series of closely set upright stones found outside the ramparts of Iron Age hillforts in northern Europe.

French: Cheval de frise literally means "Frisian horse". The Frisians, having few cavalry, relied heavily on such anti-cavalry obstacles in warfare. The Dutch also adopted use of the defensive device when at war with Spain. The term came to be used for any spiked obstacle, such as broken glass embedded in mortar on the top of a wall.

The cheval de frise was adapted in New York and Pennsylvania during the American Revolutionary War as a defensive measure installed in rivers to prevent upriver movement by enemy ships.

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