I've never seen this done before and would be surprised if you could out of the box. Your options would be to override save() etc on your Domain class and do it manually to the second database after you call super() or you could set up replication between your databases. The second option might be more desirable when it comes to data integrity.
I haven't tried this, but it sounds as you could solve your problem using the Grails Sharding plugin.
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.