The Holocaust is the name applied to the genocide of minority groups of Europe and North Africa during World War II by Nazi Germany and its collaborators. Early elements of the Holocaust include the Kristallnacht pogrom of November, 1938 and the T-4 Euthanasia Program, leading to the later use of killing squads and extermination camps in a massive and centrally organized effort to exterminate every possible member of the populations targeted by Adolf Hitler and the Nazis.
The Jews of Europe were the most numerous of the victims of the Holocaust in what the Nazis called the "Final Solution of the Jewish Question" (die Endlösung der Judenfrage) or "the cleaning" (die Reinigung). It is commonly said that around six million Jews were murdered in the Holocaust, though estimates by historians using, among other sources, records from the Nazi regime itself, range from five million to seven million.
Millions of other minorities also perished in the Holocaust in addition to this figure. About 220,000 Sinti and Roma were murdered in the Holocaust (some estimates are as high as 800,000), between a quarter to a half of the European population. Other groups deemed "racially inferior" or "undesirable": Poles (6 million killed, of whom 3 million were Catholic/Christian, and the rest Jewish), Serbs (estimates vary between 500,000 and 1.2 million killed, mostly by Croat Ustaše), Soviet military prisoners of war and civilians in occupied territories including Russians and other East Slavs, the mentally or physically disabled, homosexuals, Blacks, Jehovah's Witnesses, Atheists, Communists and political dissidents, trade unionists, Freemasons, Eastern Christians, and Catholic and Protestant clergy, were also persecuted and killed.
Generally, the residents of Grantville, hoped that their alteration of 17th century Europe would prevent genocides such as the Holocaust. Jewish Marranos Rebecca Abrabanel and her father Balthazar read the history books about the Holocaust. Balthazar in particular was so shaken by what little he had read that he could not engage the subject further.
Morris Roth's father was a Holocaust survivor liberated from the Buchenwald concentration camp by Mike Stearns' grandfather, Tom. The senior Roth decided to live in his savior's home town, Grantville, as he saw living with his new friend Tom Stearns to be the safest place.
After allying with Grantville, Gustavus Adolphus subtly conversed with Axel Oxenstierna about the Holocaust. Gustavus hoped that his survival would alter the chain of cause and effect for Germany, and avert the genocide.