How did people know that bilberry was good for night vision during World War II?

In World War II, during night bombing missions, British Royal Air Force pilots reportedly experienced an improvement in night vision after eating bilberry jam. In the mid 1960s, reference to these observations eventually led to be first laboratory and later clinical studies on the effects of bilberry on the eyes and vascular systems. More.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.