I was given the assignment to draw a cover for Action Comics' 1000th issue. 8 artists were chosen, and each was given an era of Action Comics to depict. I got lucky and was given the 1940's - easy money, really, as it was an opportunity to draw Superman vs. the Nazis in WW2. I even threw in a "buy bonds" blurb - something I'd wanted to draw on a cover for years.
Below, you can see the initial thumbnails for the cover as I worked out a couple of ideas. The concept really came together very quickly.