Imagine a unit so bad ass that over 250 years later, their operating procedures are still being used not only by the modern day light infantry and special operations units in the United States, Canada, the UK, and Australia but two units, the Queen's York Rangers of Canada and the U.S. Army 75th Ranger Regiment have taken their name. You've just described Roger's Rangers.
Roger's Rangers, under the command of Major Robert Rogers was a brutal and unstoppable force during the French and Indian War, who used creative tactics to defeat much larger forces and harass large armies to exhaust them and reduce their mobility and scouting ability.
Roger's Standing Orders became the bible for how to properly conduct reconnaissance and patrolling operations, and to this day, remains the last page in the Ranger Handbook. Their tactics combined the best elements of the Native American warriors and their European counterparts and the Rangers were equally skilled with musket and hatchet and laughed at the idea of standing in a line and exchanging volley fire, in favor of using the land around them to garner a significant advantage.
Today, Roger's methods live on at the U.S. Army Ranger School. Those that complete the course, which maintains an extremely high attrition rate, are awarded the U.S. Army Ranger Tab. To receive the tab, one must withstand significant lack of sleep, lack of food, and survive constant patrolling, ambush missions, and reconnaissance missions - the very skills that Roger's Rangers created. The Ranger Standard is so strong in the U.S. Military community, that even outside the 75th Ranger Regiment; it is very hard for an infantry officer to be promoted into the Colonel ranks if he has not attained the coveted Ranger Tab. Inside the Regiment, no member can attain Sergeant's rank without earning this honor. Rangers Lead The Way