Most of those standing in the cold were veterans.
Men who fought for him.
I am completely open to non-British historians, even if they contradict me.
I just can't find any.
Can you?

Jim, we know why men volunteered because we have their letters and diaries.
There are many reasons including all those on your sourceless (made up) list, but mostly for the reason given in your quote.
To try and stop the invading German armies.