Answer:
As early as the 17th century, many countries in Europe carried out a series of revolutions, the most prominent of which was the French revolution, the revolution that opened a series of conquests by Napoléon Bonaparte. Napoleon Bonaparte's destruction of the existing states and subsequent reorganization of Europe with the Congress of Vienna fueled burgeoning nationalism, leading to the subsequent creation of the Austrian-Hungarian empire, the unification of Germany, the unification of Italy and the tensions in the Balkan region, as well as the drastic reforms in the Russian empire. Then Great Britain and France, which were partly the Ottoman Empire, the countries known as the great powers. Unresolved tensions in Balkan, and a system of alliances known as the Triple Alliance (1882) and the trilateral alliance were the main causes of the First World War. , which itself also paved the way for the Russian revolution and ended only with the participation of the United States. The armistice left Germany with the burden of reparation, this burden, combined with the Great Depression),, created the conditions for the Fascist party of Adolf Hitler to take power, opening the way for the of the Third Reich as well as the emergence of Fascist parties in Spain (see Spanish Civil War) and Italy. Hitler's invasion of Poland, Belgium and France signaled the beginning of the World War II.