Archives and Records Administration) [Public domain], via Wikimedia Commons While it is customary to assign specific start and end dates to historical events, the reality is always more complex. The Holocaust is a case in point. Though it is associated with World War II, the ideology and infrastructure of the genocidal program were seeded in the preceding decade. The lead-up to war and genocide during the 1930s was an essential precursor to the the Holocaust and must be understood as its foundation.