USA.GOV - This is the primary entry point for finding government information on the internet. The U.S. Government puts out a lot of multi-topic information that can affect your lives. This includes military information that can help you navigate your military career.
From the links above you can access the U.S. Constitution, Declaration of Independence, Bill of Rights, Federalist Papers, Gettysburg Address, Abraham Lincoln Papers, George Washington Papers, U.S. Code, Code of Federal Regulations (CFR), Congressional Bills, Congressional Record and many more documents . . .
Library of Congress (LOC) American Memory Project - Subject: War, Military - Contains some historical primary sources (photographs, interviews, maps, etc.) While there are only a few listed military collections, if you put a term in the search box (e.g.Vietnam, or Army, etc.), you will find results specific to your topic. Or you can do the same from the home page. Just remember that these are historical documents, so more recent American events may not be covered..
Military Specific Links
Department of the Army (home page)
Department of the Army Organizational Structure and Mission
U.S. Army Press Publications From the Army University (6 magazines/journals)
(Note: to access the contents of these periodicals click on the Title link below the text describing each magazine or journal)
Army Publishing Directorate (APD) Produces numerous publications including field manuals, etc. Check out the publications tab. Note: Some are large, like my field manual example, so it may take time for them to download.
U.S. Army ROTC
University of Delaware ROTC
University of Delaware (and SU) Prospective Candidates
Salisbury University ROTC (home page)
Military Branch Websites (Courtesy of the LSU web site)
DEPARTMENT OF HOMELAND SECURITY | Website