This book examines two periods of major revolutionary change in Europe - France in 1789 and Central Europe in 1848 - to determine what forces emerged from the associated events to undermine the stability of the existing international system. Although both revolutionary periods were different, each produced the following destabilizing forces: heightened nationalism; a decline in the internationalist perspective among the ruling elites; instability among the ruling elites; conflict in the center of Europe; heightened awareness and importance of ideological differences; a breakdown in the cohesiveness of the international system; and finally diplomacy that was characterized by the pursuit of policies that had vastly greater ends pursued with greatly expanded means. Similar forces appear to be emerging in the aftermath of the upheavals of 1989, and therefore the friction in the international system will increase similarly to the past. In effect, the tentative uniformities among destabilizing forces after 1789 and 1848 will come into operation after 1989.