After World War I, the four major empires : Germany, Austria-Hungary, the Ottoman Empire, and Russia broke into smaller countries and lost lots of land. Czechoslovakia, Yugoslavia, and Poland were created out of Central Power territories. Finland, Estonia, Latvia, and Lithuania were formed after Russia's fall to Germany. Hungary, Turkey, and Austria developed because of the fall of their leaders. New French and British alliances were formed with Poland and Czechoslovakia in case of a German invasion. These same borders were one of the causes of World War II. The modern world is still affected as the borders continue to change and it is a never ending cycle of conflicts affecting boundary lines.
Ethnic Tension Grew
Ethnic groups within each empire wanted to set up their own nations, but new boundaries created problems. Participation in the war caused nationalistic ideas to bloom in many British colonies and these smaller groups began to demand independence. Once countries, such as Yugoslavia, were established, other nationalities saw that self-government was possible, and they began uprising. Many ethnic minorities lived within the borders of newly- created states. Czechoslovakia, for example, was a new nation after WWI, but it was multiethnic, so even after its creation, some parts of the country still merged with Romania. This is still relevant today because in 1993, Czechoslovakia peacefully dissolved once again into the Czech Republic and Slovakia.
Fall of Monarchies
there was a very definite shift away from monarchy after the First World War, particularly in Europe,and traditional religion these ideas were seen as having “failed” to prevent the catastrophe that was the First World War paved the way for an even more destructive conflict