--- I don't believe that people were "assigned" to the Waffen SS. They had to request it.---
Many of the Waffen SS were draftees, and a lot of them were not even Germans, as the war went on.
We can understand why Grass didn't want to be associated with the dreaded SS. Just look at the comments on this thread...
More towards the truth, but diffucult to explain (it would have been even more difficult for Grass, after he started writing, no?) was this; Not all who were drafted into SS units were bloodthrirsty murderering fascists, bent on world domination. There were plenty who just happened to be Germans of fighting age --- at a bad time to be so!
As losses mounted (at or near Stalingrad alone some 270,000 Germans died) replacements had to come from somewhere.
I rarely think of those from other countries whom ended up in German armies...that too, did happen. Thanks to claudistg for mentioning this. Truth can always help. Without it, all hope of understanding is lost.
Those Nazis running things, however, really knew how to "make an offer, that could not be refused", didn't they?
Whew! I'm glad they lost! (if you fellows are krauts, no offense, eh?)