The twentieth century, unlike any previous century, has seen dramatic changes in many different areas such as science, technology, politics, religion and society. One of the most important and certainly most evident changes is the increasing mortality of war. Sure, people have died in wars since the beginning, but in the 20th century wars began to generate much higher casualty counts among both contending armies and civilian populations, the latter being the most drastic change in the number of victims. Similarly, in the 20th century, two opposing dictatorships arose. Although both bore many similarities, they represented the culmination of two different political ideologies that had flourished in Europe since the mid-19th century. It all dates back to the First World War, which produced a disillusioned public who increasingly sought to change their life circumstances, but attempted to do so outside the established system. The two regimes are simply the two exact extremes that were produced in this reaction. National Socialism represents an ultra-conservatism that goes far beyond the boundaries of the conservatism known today, while communism represents ultra-liberalism. Because these two were so ideologically extreme on the right and left ends of the political spectrum respectively, they effectively wrapped themselves up completely, so to speak, so that they weren't all that ideologically distant from each other after all. So the question is: if the ideology of the two regimes was so different, why then were there so many similarities? What truly united them was the rejection of the same prevailing doctrine: liberalism (Overy 639). Both preached against the bourgeoisie and praised the common... middle of paper... and that a similar event would happen in the future. It is important to consider them as archetypal examples of repression born of paranoia and ideologies distorted into bizarre shadows of their former intent. Although they are the two most studied and famous, there are other regimes throughout global history that can be approached in much the same way. For example, in terms of ideology, a historian might approach Communist China, or in terms of genocide, one might approach the Khmer Rouge regime in Cambodia using knowledge gleaned from the study of National Socialism and Communism. Similarly, it may be possible to use the same knowledge to predict when a country might move towards such a regime and to try to prevent it from doing so. In this way, the legacy of these regimes is not one of terror and bloodshed, but rather of helping to prevent further bloodshed.