All armies give drugs to their soldiers. Back in 19th century Prussia sent 400,000 soldiers to war with Russia 250,000 returned as drug addicts. During WWII Wehrmacht soldiers on eastern front were taking tons of drugs, don't quote me on that I think it was called Provasil or Pervitin something like that.
Soldiers don't really need drugs for pain, but for tiredness and sleepiness. Soldier needs to go without a sleep for days if not weeks. During Gulf wars US pilots were constantly on drugs that extend wake hours.
https://www.youtube.com/results?search_query=Natzis+taking+drugs
The easiest way to torture soldiers to get information out of them, without breaking human rights laws, is to prevent them sleeping, because they are already sleep starved. That's another thing everybody is using.