The correct answer to this open question is the following.
Although the question is incomplete because you forgot to attach the excerpt from "The Origins of the Boxer Uprising" by Joseph W. Esherick, we can comment on the following.
According to Esherick, the Boxer Rebellion became such a famous historical event because it made a group of Chinese young men to have the consciousness of the consequences due China to the Western world influences and the Christian religion that some priest tried to evangelize in China.
In 1900, this group was known as the Society of the Righteous and Harmonious Fists. They didn't like and never accepted the influence of Japan, neither the Western world culture. They started to protest and violently actions like attacking and killing foreign people, Christians, and destroyed private property.
