How does john green refute those euro-centric explainations

Which of the following statements is true about germany's use of u-boats?

What pact signed on 1949 reinforce that the united states would not return to an isolationist policy

Which action by the us war department angered chief red cloud to the point that he refused to sign the treaty of fort laramie ? a) the killing of buffalo by the united states troops b) the appointment of troops to the powder river basin c) the burning of parts of the powder river basin d) the murder of chief red cloud’s wife