Militaries worldwide have used or are using various psychoactive drugs to improve performance of soldiers by suppressing hunger, increasing the ability to sustain effort without food, increasing and lengthening wakefulness and concentration, suppressing fear, reducing empathy, and improving reflexes and memory-recall, amongst other things.
Contemporary
For drugs that recently were or currently are being used by militaries.Administration tends to include strict medical supervision and prior briefing of the medical risks. Caffeine, diet pills, painkillers and alcohol are not included on the list. Non-administrated, illegally used drugs are also not included.
Historic
Benzedrine was claimed to have been administered by Allied forces during WWII, esp. by the US Germany and Japan used methamphetamine. Methamphetamine ("Panzerschokolade", "Pervitin") during WWII by Nazi Germany was the eponymous name that the Luftwaffe are claimed to have used. D-IX was a combination of Methamphetamine, Oxycodone, and Cocaine that was produced in 1944 but could not be mass produced before the war ended. It was part of a future generation of "pep pills" for the German military and was tested on concentration camp prisoners.