1. Britain actively carried out overseas expansion and slave trade to complete the first industrial revolution;

2. With the extensive development of the second industrial revolution, the contradiction between industrial strength and colonial ownership appeared, and emerging countries such as the United States rose rapidly;

3. Science and technology

4. The colony evolved into the outbreak of World War I..

5. Balkan Peninsula, Sarajevo incident

6. The signing of the Treaty of Versailles and a series of treaties constituted a new system of post-war European and international relations, the so-called Versailles system, which had an important impact on the development of post-war European and international relations. Human influence: bring profound disasters to mankind. Warning: Defend peace, oppose unjust war, actively develop economy and improve international status.