BASTION, a projecting work forming a part of a line of fortifications (through the Fr. from late Lat. bastire, to build), designed so as to bring flanking fire in front of the neighbouring bastions and along the curtain connecting them. In the following figure, A is the "salient" angle, AB and AC the "faces" of the bastion, BD and CE the "flanks." A "flat bastion" is one with a very obtuse salient angle. A "tower bastion" is a caseinated tower built in bastion form. A bastion" is formed of half a bastion with a parapet from A-F.