Hello, my brief answer concerns Finnish military during the second world war and obviously the source will be in Finnish. I hope this is ok by the rules of this subreddit. A bit of a silly worry possibly but I want to be sure that I'm not violating anything. Also, this answer will mention methamphetamine, but also drug use in general. E: Oh damn it wasn't so brief, I hope I'm not too wordy.

So, about use of drugs for performance enhancement during the second world war in Finland. I think this is quite relevant even though the original question is more about Germany, because especially methamphetamine used in the Finnish military originated from Germany at the time.

It is pretty well known that opiates have been used and are still used as pain medication. So as in, I'm sure, many other countries, Finnish military started stocking up on opium, morphine and codeine before the Winter War. At first the government was reluctant on acquiring the drugs for the military, because the government was skeptical about the war actually ever starting, even in the autumn of 1939. Still, a domestic drug company Orion was tasked on producing opiates for the military, as well was reducing the sales of opiates, and also heroin, to civilians. After the Winter War the military proceeded to stock an immense amount of drugs, for example 917kg of opium.

Heroin was used as a medication on flu, coughing or pretty much any minor inconvenience, as it was customary even in the civilian life. Even though the amount of heroin in the pills was very small, about 5mg, the recommended dosage was often not followed, because the downsides of large usage wasn't very well known. A soldier later recalled "When you had a cough or otherwise felt unwell they just threw you a handful of pills as in 'Take these!'. You didn't really understand what they were.". The medics tasked in distributing the medication were often not trained in the proper dosage. During the Finnish offensive phase, and the later retreat during the Soviet offensive, of Continuation War there were a lot of wounded soldiers, about 45% of all Finnish soldiers wounded during the whole second world war, so the usage of morphine skyrocketed.

Most well-known case of drug use during war in Finland is undoubtedly medical methamphetamine, or under the name it was marketed, Pervitin. It was produced in Germany and could there be purchased without a prescription. The German military hoarded it in massive amounts during the second world war, and even though it seemed to grant superhuman endurance, it was soon discovered that it had severe side-effects, like psychosis, hallucinations and radical mood-swings and the distribution was greatly reduced after 1940. During the late 1940 only a fraction, about 10%, of the earlier amounts was delivered to the troops. However, the newfound ally of Germany, Finland, would now receive great amounts of Pervitin, among other munitions, as a token of their friendship. Germany was quite eager to get rid off the excess drugs, which resulted in great amounts ending up in Finnish hands.

Pervitin was especially popular for the Finnish recon patrols (I'm not sure about this translation. The original Finnish word is "kaukopartio". They engaged in recon behind the enemy lines, but also carried out kind of guerrilla activity, ambushes and the like, against the enemy. They traveled pretty famously by skis. ). The patrols had to perform stressful long-range operations where rest was scarce and the possibility of death not too unlikely. Even though the importance of safe dosage was emphasized, the stressful nature of the patrols often led to too large doses. a famous story, which might be a tad exaggerated, recounts an adventure of Aimo Koivunen, a recon patrol soldier, who overdosed on Pervitin during an operation, during which the patrol had been on the move for 3 days with little sleep or food. By his own account, he just grabbed a handful from his pocket and downed them all, after which he started to hallucinate. At some point during the mission he separated from from his group and was lost for 14 days, during which he ski'd into a landmine.

Pervitin was also used among the officers. During the later stages of the Continuation War, a high ranking officer Adolf Ehrnrooth greatly used Pervitin and sleep medication; one to stay up, the other to be able to sleep. Also the accumulation of wounded soldiers led not only to the increasing medication for the wounded themselves, but also required the medical staff to take drugs to be able to work the stressful hours.

The drug use during the war was a large reason for the spread of drug abuse among the civilian populace. During the war many soldiers had been addicted and took their malady back home. Considerable amounts of narcotics had been left in the pockets of returning soldiers, which then started spilling into the streets. The legislation was also lagging behind concerning new information about the abuse of some substances that had earlier been used as regular medication, such as heroin.

Source: Mikko Ylikangas: 'Unileipää, kuolonvettä, spiidiä: huumeet Suomessa 1800-1950' ("Sleep-bread, death-water, speed: narcotics in Finland 1800-1950").

The Finnish story is great!

As for relatively current use, I remember a few years back there being a big to-do about the US air force using amphetamines in 2006 when a B-1B crashed while returning to Diego García. Amphetamines and some sort of sedative both were standard issue for pilots, as reported in this Christian Science Monitor piece from 2002.

What I am curious about is whether there is a "fighting drug" tradition other than the modern use of speed, documented at all through history, since it would make sense that soldiers would take any advantage available, yet this is not a widely discussed aspect of historical military engagements.

Medicating soldiers for one reason or another during war was pretty common. You wouldn't normally think of alcohol as a performance enhancing drug, but it was frequently used to steel nerves or as a reward. "Rum rations" used to be standard in various navies. I recall reading an article for one of my Canadian history courses about how in WWI, Canadian soldiers were given a daily rum ration to prepare them for battle. This was decried by prohibitionists at the time, but the military claimed it was necessary. I don't have access to an academic search engine and this would have been in a course pack from like 2009, but this other article seems to be a pretty decent casual-reading source on the matter, if a little florid (though it doesn't mention the prohibitionists, it does talk about teetotalling officers and how that attitude played out with the troops): https://legionmagazine.com/en/2002/09/rum-in-the-trenches/