Among the Known Worlds discovered and explored by Marcus Americanius Scriptor, Germanias were the Earths on which Nazi Germany won World War II. They were separated from the Romas by the Divide; Scriptor suspected that more clusters existed beyond further Divides.
None of the Germanias were entirely ruled by the Nazis. On over half of them, America stayed out of the conflict. On a tenth of them, the Germans signed non-aggression pacts with the Russians. On a further third, the United Kingdom either surrendered to or allied with Germany. In universe beta alpha one five, Ernst Rohm killed Adolf Hitler circa 1933 and declared himself Führer.
In some worlds, Nazi power was so consolidated and entrenched that the Empire of Empires chose not to interfere. In one, America was divided between the Nazis and the Japanese, and the Germans had developed remarkable technological advancements such as moonbases, rocket-planes, and the draining of the Mediterranean Sea. In another, America and the Nazis had been locked in a stalemate for several years, and President "JPK" was reaching out to Hitler for negotiations. (PROSE: Warlords of Utopia)