Battle of Britain
The defence of Stalingrad
I pretty much revere any person who has been in a proper war. Regardless of the conflict or side, what it must take to put yourself in the firing line for your country away from your family, especially when they are in peril at home like in WW2. The courage of the average seaman, soldier, pilot etc is outstanding to me.
I think that a lot of the conflicts of the early part of the last century bred a special generation of people who learnt about their own moral code and respect inadvertently through conflict. That generation didn't take much for granted subsequently and these days it's easy to see why so many people, who haven't known that kind of sacrifice are unable to take responsibility for themselves.