I'm not sure how many lives you're "saving" if you end up having to drop atomic bombs on German and European cities. Just to pick one example, Berlin in 1945 had a population of 2.8 million.
Further, the fallout from the bombs dropped on Japan basically blew out to sea. Bombing Germany? Contaminate Western Europe?
And it wouldn't just be a year. We had three bombs. What if you drop a demo bomb and Hitler said, "Screw you?"
Going to keep bombing German civilians?
The real problem here is that it's easy to armchair quarterback after the fact. It's easy to say, "Hey, they could have waited." Knowing again, after the fact, that the top-secret bombs actually were going to work.
Hate to say it, but maybe stick to energy policy?