It was the largest rescue of Allied airmen behind the lines in the entire war
Why not post 400 links, all referencing the exact same individual's memoirs?
Felman's account makes it clear: one of the five or six factions fighting for control of Serbia in 1944 - specifically Mihailovic's Chetnik splinter group - helped to airlift out Allied airmen.
Why did the Mihailovic column have to do this? Because other Serbs, like the Pecanac faction of the Chetniks or the Nedic VNS forces wanted to find and kill them - as did the Germans and the Italians.
"The Serbs" in general did not rescue these men. Dragoljub Mihailovic and his small group of supporters did, and he rescued them from other Serbs who would have killed them.