http://www.history.army.mil/html/bookshelves/collect/usaww2.htmlThe U.S Army in World War II: the 'green books' published shortly after the war ended, for anyone who's interested in this subject, worth checking out, you may not know about these books.
I have the original printing of 'The Battle of Okinawa', gotten by my father who was there during the battle with the 27th Infantry Division, 102nd Combat Engineers.
This one is published in its entirety on that site, all 529 pages, including maps and photos, and contains an amazing inch-by-inch account of the battle.
Not all of the green books have been published online but there are references by title to the entire series. Long ago I saw some of these in an obscure part of the University of Miami library.