A hornwork is an element of the trace italienne system of fortification. It consists of a pair of demi-bastions with a curtain wall connecting them and with two long sides directed upon the faces of the bastions, or ravelins of the inner fortifications, so as to be defended by them. The hornwork was used to extend the fortified area in a particular direction to prevent the enemy occupying an area of high ground or simply strengthen the overall fortifications in the expected direction of attack. A crownwork serves a similar purpose, but unlike a hornwork, it contains full bastion.