He fled to Memphis, Tn in 46', changed his surname to "Albertson", and married my great-gandmother; who grandson is my father.

I never met the man, but sometimes when I look into the night sky I feel my blood boil.

Learn more about his life and maybe then you can forgive him.  If he wasn't participating in the Holocaust or other atrocities,  then he was probably like any other drafted soldier - maybe he agreed with the Nazis and maybe he did not.  Germans had less chance to publicly disagree with their government and fewer chances to leave the country then we can ever imagine.  Watch the movie "Swing Kids" to get an idea of what teenagers went through - including brainwashing in school and in the youth groups.  Most young men did not have a choice about being in the Hitler's youth groups and being drafted into service.  After you know what he went through and what he did in the war, then decide if your blood should boil or if you can be glad he had the chance to come to the USA after the war.

I have a good friend who was in the Hitler Youth - in the last months of the war, he was drafted into the German army when he was 15.  He had no choice.  If your great-grandfather was not in the SS or the Gestapo and was just a regular German soldier - then he was just doing what he had to do.  Hindsight is easy for us - we weren't there. 

Interesting bio Jesse.  I think the first question I would ask is why does it bother you?  You have nothing to do with whatever any of you ancestors may have done. 

Other then that the responses you have received so far are right on.  Many people had no choice in being members of the Nazi party and conscription was used in our armed forces as well as Germany's.  I use to have a neighbor who's father was in the German Army during WWII.  He was taken POW, held in the US, returned to Germany when the war was over.  He came back and became a US citizen.  In Germany he was a farmer, drafted into the army.  He (and his family) lost their farm and everything they had because of the war. 

Putting aside some of the atrocities, the German people had good reasons to support a change in their government although that's another topic all together.

If my relatives who were ordinary humans could face ugly choices in Nazi Germany, then it must be possible for any human, including me, to be faced with ugly social choices.  How can I understand them in order to understand myself as a human?  Would I be brave and resist like those Swing Kids or be afraid and passive?