The commander that I choose to track was Col. C. Carroll Marsh of the twentieth Illinois Infantry. From the maps, I think I was able to get a general sense of where the unit was on the battlefield, but the more detailed primary maps were more useful than the map in Battle Cry of Freedom. The commander wrote many times that he was by a certain regiment, river, or batteries, so the primary maps that I found that had those details displayed gave more of an ability to track the unit. Where I had trouble tracking the unit was in how the commander used language like “backwards”, “forwards”, “left of McClernand”. From the Civil War Trust video, it seemed like on day one the union troops were only moving backwards and then on day two push forwards, but Marsh’s account has the Union troops moving various different directions. It was confusing to know if the units perspective on the battlefield was the same as mine viewing from the maps. There also were maps that did not have a scale, making it hard to determine if the amount of ground Marsh was covering was possible if the map accurately depicts the movements in the report. Other sources I would consult with are other reports from the same unit or surrounding units in the area of McClernand and Sherman to compare with Marsh’s report and better understand which directions he was moving. This could help verify what commander Marsh wrote in his report and also help clarify how the unit was moving. I believe the biggest challenges historians face when attempting to use primary written accounts to explain the way battles were won or lost are trying to follow the language/directions of a report in relation to maps, reading the writing on older maps, being able to find the same location on multiple different maps that have different portions or view the battlefield from a different angle, also discerning the accuracy of a report considering that it was not written during the battle, but after.