Why do we research history? We should learn from things that were made in past. Why do we research history? History is a series of things that happened in the past. Those things that are happened in history can use to make models for the future. Research of history is the thing. That purpose is to find the things that will happen in the future. The key question in the history research is to find answers for the questions like "what made something happen"? What mistakes were made in cases that are under the research? And what did people learn about those cases? Another thing is that that the purpose of the research of history is to find the answer to the question "what should we do in similar cases"? What went wrong? And what went right? When we are thinking about questions like "which side had better generals Confederate or Union side in the United States civil war?". We must realize that the thing that fights is the entirety. Even the best generals