Operation Gladio strongly intervened in the transition period of spain, helping arrest the momentum of leftist and anarchist groups in favor of christian conservative ones.We never had proof of their intervention in the Scala case but they were one of the main suspects. Also of financing many, many right-wing ultraconservative paramilitary groups.
Some even say they had a hand behind the failed coup of 1981, helping the government trigger a soft-coup (a bit like what erdogan did shortly after getting his seat) to dismantle the structure before a more firm coup would stablish.But that one is doutful as CESID (our NSA) was already getting good at dismantling military coups.