Try this link to Fort Leavenworth.
http://cgsc.leavenworth.army.mil/CARL/index.asp
They have a large number of manuals that are obsolete in PDF files that are easily downloaded. If you go back to the 1950s and 1960s you will need to use key words such as counterinsurgency (look for the 1963 field manual US Army in COIN) and counter-guerrilla operations as FID was not yet invented. Also you will need to look for Low Intensity Conflict.
Bookmarks