The Internet contains many websites focused on United States and world military history. For academic and scholarly research, care should be take to ensure that biased information is not used. When in doubt, check library resources or ask a librarian.
U.S. Civil War
World War I
World War II
Vietnam War
Each branch of service in the US Armed Forces has a recommended reading list. Some are specific for certain fields, others for certain grades. Reading any of the recommended books will make you a better scholar and warrior.