During WW2, german troops were issued a stimulant under the trade name "Pervitin" which is now known to be methamphetamine, more commonly known as "Speed" or "Crystal Meth".
Based on anecdotal evidence, it seems to have been regularly used by many soldiers, including Panzer crews and pilots.
http://www.spiegel.de/international/...-a-901755.html
http://www.spiegel.de/international/...-a-354606.html
Hitler was also taking methamphetamine regularly from 1942 on, which explains a lot...
The Allies used amphetamines during WW2, like "Benzedrine", although its use seems to have been more tightly controlled, although it was handed out to Allied bomber pilots on long flights.
In Montserrat's "The Cruel Sea" (1951), there is a scene late in the book where the frigate "H.M.S. Saltash" has been hunting a U-boat for a long time. The captain who has been up for 24 hours asks the ship's doctor to give him something to stay awake. After some hesitation, the doc gives him Benzedrine and tells him : "This will keep you up for 24 hours after which you will go out like a light and wake up with quite a hangover". He also admonishes him that Benzedrine is not something to be trifled with, to which the captain replies that he is not planning to make a habit out of it. Montserrat served in the RN in WW2 and the book was based on his wartime experiences. It is a novel, but it does show that even in WW2, it was common knowledge that amphetamines were potentially dangerous.
Amphetamines like "Benzedrine" are also supposed to be less potent than methamphetamines like "Pervitin".