Some here may remember this history book.
Arming America: The Origins of a National Gun Culture (New York: Alfred A. Knopf, 2000) by Michael A. Bellesiles is the only book in the history of the prestigious Bancroft Prize to have had its award rescinded. http://en.wikipedia.org/wiki/Arming_America
Also this 56 page downloadable paper on it.
I remember when that whole mess blew up. As I recall, that wasn’t so much a case of plagiarism as of outright fabrication of cited data (the “probate records” that he suddenly couldn’t account for, and that nobody else could find or cite parallel examples).
Best part was that he wasn’t brought down by the NRA or other “likely sources”...he was exposed by his fellow historians!