Chevaux-de-Frise (Fr., 'Friesland horses,' so called as having been first used in Friesland during the wars of the 17th century) is a military obstacle of the form shown in the figure. It is difficult to make unless skilled labour and the necessary materials, such as iron railings, gas-pipes or hop-poles, are at hand, but is kept in a fortress as an article of store. The pattern used by the British army consists of a cylindrical iron tube, 6 feet long and about 5 inches in diameter, pierced with 12 holes to receive as many spears of the same length, which are packed in the tube when not required. Several lengths connected by chains may be used as barriers or as obstacles in the ditch of a fort, or in any place where required. It is, however, generally easy to roll them out of the way, though at the siege of Badajoz, during the Peninsular war, one formed of sword-blades fixed into beams of wood, and placed in the breach, was found to be a very serious obstacle by the British storming party.