I used to know a man who was a Spitfire pilot in the Battle of Britain. He said that the survivors each night would descend on the local Pub, and get absolutely plastered. As RAF heroes they could do no wrong, and the locals kept shouting them drinks, so it was easy to over-consume alcohol. There was no such thing as a breath test in those days so no way to judge whether a pilot was 100% sober the next morning. He told me that the worst hangover can be cured in 30 seconds by breathing 100% oxygen from their altitude breathing gear.

Three of my uncles met up at the battle of Monte Casino, a tank driver, an infantryman and a medic had not seen each other since 1939, yet all took shelter in the basement of the same demolished Italian house. They discovered that the basement was actually a wine cellar and spent the next two days drinking it dry.

These are stories by people who were there, “first sources” I think you call them. It is a small sample size, but I think alcohol abuse was common in all military forces in those days, whenever they could get away with it.