On just about anything war related: http://www.ahco.army.mil/site/auth_docs_brief.jsp Search to search, Browse to Browse everything. Lots of info, so I suggest the search.
Definately a valuable resource. I found it a couple of days ago, and I've been downloading tons of manuals. Just a word of warning: some of the manuals are listed as being from WWII, but are in fact from the fifties and sixties.
. This site is dangerous , I nearly drowned in " casey"s handbook for batallion handling from the civil war 1862 .