Greetings!
Azure:
Over 1800 years ago, in the first century AD, the Roman Empire fielded several special forces along the Northern Fronteir. These special operations forces were several groups of about 2000 men, all of whom were specially recruited from various regions of the empire. They were also selected for special skills in woodcraft, hand-to-hand fighting, and languages. These forces were highly skilled in operations against the germanic barbarians, of which many of these special soldiers were descendents. They operated deep behid the enemy lines in the dark forests, making raids, wiping out villages, gathering intelligence, and disrupting barbarian forces all along the frontier. These special forces were renowned for their courage and ferociousness. However, after several years of them operating with great success, rival generals, commanding more conventional Roman Legions, began to become ever jealous of the success and fame of these special forces. Through political influence, these special forces were gradually disbanded.
At different times, throughout the Roman Republic and also in the Byzantine Empire. special forces were raised, trained, equipped, and deployed for action throughout a variety of campaigns.
In Caesar's day, there were special groups of Peltasts--unnamed often, sometimes with unique signifiers or uniforms, sometimes not--who were regulalry deployed as special forces to go behind enemy lines--or, as it were, way out in front of your own--and harass, disrupt, and slaughter the enemy, before melting away into the wilderness before heavier forces could track them down.
In the Byzantine Empire, there were special squadrons of naval forces--ships, archers, and marines, that operated with specially trained and resourceful units of cavalry. They would frequently set sail for the barbarian-held coasts, make landings, and ride roughshod through the countryside burning and killing, before meeting at a predetermined coastline to rembark upon the fast sleek ships, and depart into the mist. The Byzantines became experts at such complex, combined operations, often operating with only a few thousand cavalry, for long periods behind enemy lines, and always outnumbered. Their lightning raids and superior skills set up the training, and confidence, for Byzantine arms to gradually reconquer much of the Western Roman Empire that was lost to the barbarians.
There are more that I could give. I hope these inspire you with some historical examples.
Semper Fidelis,
SHARK