The cheval de frise (plural: chevaux de frise) was a medieval defensive obstacle 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 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.