My wild-ass-guess is that, since you're setting the destinationWeb to null, at the end of the using block it tries to dispose of an object that isn't there and blows up. Remove that statement and try.
This might not be related to your error, but I see two things with this code.
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.