It would probably be very hard to find guinea pigs that precisely match the size and coloring of your son's pets, so he is sure to suspect something is up. It would be better if you tell him they got sick (being eaten could be a bit traumatic) and arrange for him to choose his own guinea pigs as replacements. Don't pay for them though; that should be the responsibility of the careless dog owner.
While the easy thing to do (If you can find exact replica's of your son's old guinea pigs) would be to quickly replace them, I honestly would say this is one of those 'learning experiences'. I used to have a Rabbit when I was younger, which ended up being eaten by local Foxes when I was 6, and it was actually the first time I experienced losing something I cared about. I honestly think it'd be beneficial to just tell your son the truth, rather than lie to him about it.
Small lies turn into bigger lies, and eventually, you've got a whole mess that you really don't want to have to deal with.
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.