The CIA is the successor to a historic organization, the Office of Strategic Services, which ran guerrilla operations in Europe and Asia during World War II. But the CIA has a cadre of shooter that live in the shadows, the Special Activities Division which typically recruits former special operators and sends them on covert missions around the world.
The OSS's Special Operations Branch focused on covert action and guerrilla support, most famously providing assistance to groups fighting Nazi forces in Europe. The SAD is probably best known for its role supporting tribes friendly to the U.S. in northern and southern Afghanistan and for being the first American forces into the country after 9/11.
If either side was forced to fight in the other's preferred format, if the SAD had to fight while leading a guerrilla force or the SOB had to fight without one, that side would lose. The SAD has better assets in a firefight, like drones and former Delta Force warriors, and the SOB has more guerrilla experience.
But if each side fought in their preferred format, then that'd be a fair fight. The SOB leading hundreds of trained French Partisans might have a chance to overcome the SAD's technology advantage.
The resistance fighters and their SOB handlers would attempt to draw the SAD into an ambush, but the SAD is unlikely to fall for any cheap traps. With dedicated drones, pilots, and their own intelligence assets, it's likely that they would get the jump on the SOB.
Since the SAD can call back for air support and has night vision, the opening moments would go badly for the SOB and their fighters. Precision strikes would rain through darkness, breaking up fighter positions and killing dozens. But the partisans trained by the SOB were no slouches and would quickly move to overhead cover — strong buildings if they're available — but anything from trees to rock overhangs if necessary.
The SAD would have to attempt to take the objective at some point, engaging in direct action with the SOB and the surviving partisans. With Thompson submachineguns, BARs, M1 Garands, and other weapons, the SOB could inflict serious damage even if they were recovering from the airstrikes.
The people who fought Nazis in Nazi-held Germany aren't slouches. But they also weren't supermen, and they would eventually lose.
Despite SAD's numerical disadvantage, it would eventually win. The SOB and their fighters would lose track of what shooters in the night were friendly and which were SAD. But SAD, wearing night vision devices and likely IR indicators, would know at a glance who was who.
The SOB would be firing from the hip at sounds while the SAD could hit SOB agents using laser designators.
And if the SAD took heavy fire from any one location and were pinned down for whatever reason, they could always call the air support back for more targeted strikes, giving them space to maneuver and likely killing a few more OSS agents and their French fighters with every helicopter or bomber pass.
Luckily, the OSS never had to fight the SAD. And when it came to fighting Nazis, the OSS and their British friends in the Special Operations Executive were unrivaled.