Editing Setting:Brighthammer 40,000/2nd edition (section)

=== The Catachan ===
They move as swift as the wind, invisible as a shadow, and strike with ruthless precision. The Catachan Jungle Fighters are the subtle knife of the Imperial Guard, whose strike and fade warfare style leaves them feared and respected by friend and foe alike.

Raised from the Deathworld of Catachan, these fearless men and women are absolute masters of all arboreal terrain. A single squad of Catachans, and it is rare to see more than that in any campaign, can be dropped behind enemy lines, and use their small-unit tactics and improvisation to let them punch far above their weight.

Nowhere was this more evident than in the legendary operation on Amoz-7: In a single night, a lone squad from the 24th Catachans eradicated an Eldar pirate base and rescued more than 90 civilians, without losing a single civilian and only suffering a broken arm during the fierce fighting.

The long and short of it, Rambo First Blood Part II stealth scene.