 Complete the following phrase:  The flame fougasse has remained in army field manuals as a battlefield expedient to the present day. Such weapons are improvised from available fuel containers combined with standard explosive charges or hand grenades and are triggered electrically or by lengths of detonating cord. In some designs, detonating cord is used to rupture the container immediately before triggering the propelling charge. In order to guarantee ignition, the improvised devices frequently feature two explosive charges, one to throw and the other to ignite the fuel. Weapons of this sort were widely used in the 