You might claim that the final Fall of Rome in Western Europe came in the 16th century with the division of Western Christianity between Roman Catholicism, which up until that point was the one Christian Church, and the new kid on the block, Protestantism.
Protestantism itself soon fractured into many different sects.
In Germany the man who first set the fire of Protestantism burning was the catholic friar, Martin Luther, in 1517. A second 'Protestant' leader who also proved influential in Germany was the Frenchman from Geneva, Jean Calvin. Both men gave their names to their Protestant movements, that is Lutheranism and Calvinism. Germany has ever since been divided between Catholic and Protestant Germany. Today 34.5% of Germans claim to be Protestant, and 32.2% Catholic.
These religious differences led to political clashes, and worse, between the differing forms of Christianity, and in Luther's case especially a deep rooted anti-Semitism. These differences were replicated across Western Europe, but worse was to follow between 1618 and 1648 when the so called Thirty Years War racked much of Northern and Central Europe with Germany at the epicentre. It has been estimated that the war cost 4.5m to 12m dead of a European population of some 75m (but many countries were not involved in the war). Statistics from the period are always open to question but the raw data says this war was one of the most bloody in European history in percentage terms of the whole population.
These two centuries had an impact on future German history, not least around the question of Unification in 1871; and, as for Luther's anti-Semitism, which remains an issue in the Germany of the 21st century, the case that it had an impact on later Nazi anti-Semitism seems unquestionable.