It has long been known that German soldiers used a meth-amphetamine called Pervitin in World War II. But tales of Nazis on speed obscured the other side of the story: the massive use of stimulants by British and American troops. (Secrets of the Dead)
Very true. We still used them until at least Viet Nam. I knew an intelligence officer who was in Viet Nam during the Tet Offensive. He told me that amphetamines were passed out like candy. He also told me that when he finally got a chance at sleep, he crashed hard and felt very depressed for several days.
The longest I have stayed awake is 78 hours (long story). From personal experience, my judgement and short term memory started degrading at about the 24 hour mark and by 72 hours my short term memory was shot. I could not finish sentences, because I forgot what the first few words of the sentence were.