Setting fire to the elephant grass is a military tactic that was really used during the Vietnam War. The 'elephant grass' is a Vietnamese kind of grass that is usually six feet tall or a little more. Inside this kind of grass, complete groups of people can literally disappear. Despite the fact that elephant grass is not bulletproof, it can make people become invisible anyway.
Setting the grass on fire was a technique used to force the enemy to come out into the open.
History books tell us that this technique was often used by the Vietcong against SOG teams.
They surrounded them and then set the grass on fire.
In the second Rambo movie there's a change of parts: Rambo uses this technique against the soldiers chasing him.
