10-15 Page Topics:
1. The Peaceful War (An Examination of the Cold War Through MAD, Proxy Wars, and Diplomatic Triggers)
2. Beating a Dead Horse (The Transition of the Calvary of the Civil War to the Mechanized Calvary in WWII)
3. War with Depth (The Evolution and Usage of Submarines in U.S. Warfare)
4. The Super-soldier Project (How the Infantry Unit has Become Better Trained and Equipped to Operate in Increasing Smaller Units).
I would advise against talking about trains because their relevance post Civil War is limited in the United States and the more interesting usage of trains was by Germany in the World Wars and that would be beyond the scope of US Military History.