Bolt position (military)
The bolt position is a defensive military position . Its purpose is to prevent an enemy who has broken through the neighboring front section from rolling up the front from there . It runs behind the front usually at right angles to it and is mostly through temporary field fortifications as tank traps and rifle or ditches or permanent fasteners such as bunker strengthened.
Examples are the Ettlinger bar or the Orscholzriegel as part of the Siegfried Line .
Anti-tank barriers ( dragon's teeth )
German trench in the First World War
Wehrmacht soldier digging a foxhole in World War II