Answer the Question and Engage the Reader
The first job of your thesis statement is to answer the question assigned by your teacher. Make sure that your thesis doesn't merely use the prompt as a slant to discuss something else. For example, if your prompt asks you to analyze the progress of the Civil Rights Movement, don't use it as a vehicle to simply discuss the assassination of Dr. Martin Luther King Jr. However, by following the development of one person during that period, such as Dr. King, you can provide unique insight into your topic and engage the reader by focusing on the human condition of the few as opposed to the masses.
Identify your Evidence
All thesis statements require that you support your claims with evidence, and a History essay is no different. Make sure you have sufficient source material for any claims that are not considered common knowledge, and when possible, identify these resources in your thesis statement. Doing so will lend credibility to your argument and prepare the reader for a discussion that is backed up with evidence. Also keep in mind that some of your evidence might be open to several interpretations, which will invite readers to dispute your claim and open the topic up for conversation, all of which are results you want from your thesis.
According to the Department of History at The University of Iowa, your thesis statement also needs to have a focus that guides the reader through your subject from a specific perspective. The Department of History website suggests: "If your paper topic asks you to analyze women’s domestic labor during the early nineteenth century, you might decide to focus on the products they made from scratch at home." The more specific you are in your thesis, the easier it is to stay focused in developing your argument throughout the essay.
Refine and Revise Your Thesis
Sometimes, after you've crafted what seems to be a strong thesis statement, you write your first draft to find that you've constructed an equally strong argument that doesn't quite align with your thesis statement. When this happens, accept that you refined your understanding of the subject by writing about it, and then go back and refine the thesis statement so that it matches your argument. You might be tempted to re-write the entire essay to better suit your original thesis, but reworking the thesis takes significantly less time. Do more to tighten and focus a your argument and make sure your thesis matches with this argument.