First world war started as a reason of fear and anxiety between the east and west European countries. it all began when the prince Archduke Ferdinand was to be crowned and on this occasion , went to Sarajevo, the capital of Bosnia. There he was shot dead by a group of men. as a result , the world nation grouped themselves into triple alliance(Britain, France and Russia) and triple entente(Germany, Italy, Austria and Hungary). The result of the first world was signing of the Treaty of Versailles and formation of the league of nations. But , the rise of Adolf Hitler and Benito Mussolini, the league of nations couldn't prevent the occurrence of the second world war. The immediate cause for the second world war was Adolf Hitler's capture of Poland , by violating the rules of the Treaty of Versailles. This time too, the world divided itself int allied powers(Britain , France, USSR) and axis powers(Germany , Italy and Japan). This was a very fierce war as it involved massive destruction-Hiroshima and Nagasaki bombings. On the end of the second world war, the UNO was formed , but , the hostility between USA and USSR still remained for quite some time until the UNO came into power.