At the time 1900s, we mainly see how many countries try to industrialize such as Germany from an agricultural country become a very powerful country due to steel industry. Germany was not a strong country in Europe in the early 1900s, but since their discovered the coal, iron and the strong potential, they became powerful and affected strongly to the world until World War II. Because of the numerous resources it made Germany to the most modern industry country in Europe and along with it was power. Since Germany had power they start to have issues and conflict in politics. Because of the conflicts and the power, Germany believe that they had to expand their country. They need more territories, colonies and more resources to compete with England and France. And from here, in Germany started to imperialism.
In 1900s, we could see that is was very important to expand the country and with USA it was not exception. The United States joined the war with Philippines to help their independence but shortly after that they asserted that they were tried to civilize the novice. This was just a reason for America to expand their ruler, because in Europe there was a race between Germany and England in industrialization. This could be a very good reason for the guerilla warfare because the Filipino was tried to reclaim their country and their independent from the USA. The United States ruled Philippine over Spain by fighting with them because of colonial violence but then applied exactly like what Spain did.