Improvised Ambush is a tactic used by the Gurkhas.
An example is the Battle Kohima were 30 Gurkhas applied this tactic against 80 Japanese infantry man. A Japanese patrol party is heading down a jungle trail and a Gurkha scouting party sees the patrolling Japanese. They head back to notify the Gurkha lieutenant, who knows that he must find a way to destroy the Japanese patrol party. In order to do so, the lieutenant sneaks a majority of his troops down a jungle trail section that the Japanese infantry had already passed, but also sneaks a small group of his troops down a section of jungle the Japanese have not passed yet. When the Japanese scouting party get to that section of jungle, the small Gurkha troops rise up out of the jungle and ambush the Japanese infantryman with their kukris taking one, two, three infantryman at a time while the infantryman are still unsure what is going on. The Japanese patrol party starts backing into itself, unable to flank the Gurka position because of the jungle terrain, so they start moving back down the same path they came and are then ambushed by the larger troop of the Gurkha soldiers that have already started lying in wait for them there, wiping them out.