What were the costs and benefits of fighting in the war for american indians

When conducting research for forming a hypothesis, which practice should historians follow?

The date a source was created is considered part of its historical context intended audience purpose point of view

Plz ! after the first battle of bull run general ivan mc dowell was removed from command of the union army he was replaced by a. general ulysses s. grant. b. general george mcclellan. c. general robert e lee. d. general george meade.