Barry Petersen's Tiger Men. Personal memoir of an Australian AATV officer who trained lead an army of Rhade tribesmen in a semi secret war against the communists. Australia's real life Col Kurtz, if you like. He kept them out of the fighting during the Montagnard Revolt of 1964 against the SVN government. The Montagnards being no particular fans of any Vietnamese, be they Northern or Southern types.
It's particularly interesting from the what it reveals about the tensions with both the SVN government and the CIA who initially financed and ran all the SF operations with the indigeneous peoples. Petersen refused to participate in a proto Phoenix program of targeted assasination and elements of the CIA threatened him with assasination.