The first step is to develop a well- honed thesis statement. It should articulate a connection between all three domains in the greater understanding of the Civil War. The topic is there, and now the words to guide the thesis statement need to be assembled.
Once this is done, I think that you can find specific examples in each realm that can help to support it. For example, selecting works of literature that help to enhance the Civil War understanding is going to be a challenge. This will involve surveying the works of authors like Whitman, Crane, and Bierce, as well as looking at slave narratives and letters from prominent Southerners such as Robert E. Lee. Surveying and finding examples of literature that help to develop new understanding of the Civil War is going to be essential in the topic's progression.
Art from the Civil War will be handled in the same manner. Finding art samples that increase one's understanding of the Civil War is going to involve sifting through what is available, for example daguerreotypes and paintings and sketches. Being able to critically analyze how samples of art help our understanding of the Civil War become greater is going to reside in selecting meaningful samples of art and applying them to the greater understanding they reveal about the Civil War.
Finally, being able to focus on how historical research has played a role in enhancing understanding about the Civil War is probably going to focus on how the Civil War is one of the most actively researched topics today. Focusing on recreation and historical societies, as well as the role that the event occupies in our history today will be critical in this process. The web can be a great source for this, but in the end, identifying modern examples of Civil War scholarship that have enhanced understanding about the topic is going to be dependent on what is there and how it is presented.