Should the first paragraph describe the war first and then should I do a comparaison by writer?suggestion
I am assuming that the paper is a historical one, since it is in the history section. If you are writing a comparison paper, you need to realize that usually there are many things to compare. So, you will need to be selective. Good papers are always selective. With that stated, the first paragraph should contain your thesis statement. You can think about your thesis statement and your main point, the very thing about which you want to persuade your reader.
In this paragraph or the next one, you want to also give a road map of what you will be contrasting or comparing. These are your supporting points. Let the reader know where you are going. Also this will benefit you, because your road map will keep you focused on your thesis. Great papers stick to the thesis.