Yeah you need to have a variety of sources for whatever you do, not just historians but experts in the relevant field (in this case warfare/military) as well as things like eyewitness accounts etc.
Even if you don't end up including references to all of these secondary sources it's useful to have an understanding of them in order to gain a greater understanding of the topic you are researching.
In my MRP, for example, I included the work of a journalist as it provided the fundamental controversy for my topic. I also used a wide range of source material not just for analysis of historical opinions but as a means of understanding the topic so that I was better able to form my own judgement.