by 1937 they had really started looking into the effects of Benzedrine ( a amphetamine) but it's seen and used from time to time and it's use is laced across pop culture.even into the modern era.
A few notables are REM, The Red Hot chilli peppers, Elton John, I think Even the Novels Of Ian Fleming have Bond occasionally skipping the Vodka Martini for a Hit of Benzedrine.
It was not until the 1970's that Controls were placed on some drugs particularly for Benzidrine the UN Convention on Psychotropic Substances of 1971 And the US Comprehensive Drug Abuse Prevention and Control Act of 1970 along with later amendments. Then Bennies fell out of Legal favor.
In regards to military use, Pep pills are typically legal types most of the time the same things you can get at a GNC or with a Prescription atleast that's my understanding of the US DOD official line.
Beyond that has been accused from time to time with no solid evidence beyond individual use.
Around the World it's a mixed bag Accusations of Doping for some, Undeniable cases of others. as time has gone by though the culture has changed and where in the early 20th century products were more available and more openly accepted like Cocaine, Benzedrine and the like as time has gone by Culture as changed and knowledge of the risks of such products have altered. Yet the needs to push the boundaries of Human endurance and performance mean some will always be looking to find some edge the question is at what price.