They also gave amphetamines to SF guys. In the end it made them way to jumpy to be effective.
Actually amphetamines are still used with Air Force pilots to amazing effect.
From Wiki:
Amphetamines have been, and are still used, by militaries around the world. British troops used 72 million amphetamine tablets in the second world war[50] and the RAF got through so many that "Methedrine won the Battle of Britain" according to one report[51]. American bomber pilots use amphetamines ("go pills") to stay awake during long mission