1911 Encyclopædia Britannica/Chevaux-de-Frise

CHEVAUX-DE-FRISE (French for “Friesland horses”; the Dutch Vriesse ruyters, “Frisian horsemen,” and German Spanische Reiter, “Spanish horsemen”), a military obstacle, originating apparently in the Dutch War of Independence, and used to close the breach of a fortress, streets, &c. It was formerly often used in field operations as a defence against cavalry; hence the name, as the Dutch were weak in the mounted arm and had therefore to check the enemy’s cavalry by an artificial obstacle. Chevaux-de-frise consist of beams in which are fixed a number of spears, sword-blades, &c., with the points projecting outwards on all sides.