Why was ww1 so important to US history?

Morning how ur day and quick question who started the civil war?

What is one way that the congress of vienna changed the map of europe?

Why was it decided in potsdam that certain industries in germany would be disabled? a. to deplete resources that might prevent germany from coming to power again b. so that a portion of the eastern region of poland would be fused together with the soviet union c. to allow the allies to focus their war efforts in fighting the last part of the war against japan d. to provide economic aid for iran's government since large war demands were made on them