If I am correct, you are asking about the Civil War. In that case, the Mideast and Midwest were the locations for majority of these battles. Although, I would assume the more correct answer would be the Mideast for the simple fact that Virginia was the host of more than 120 principal(important) battles. This makes sense because the runner-up state to this number is Tennessee with 38 principal battles. With all this information, your answer is most likely the Mideastern or just eastern part of North America.