In the Year of the Pig (Emile de Antonio, 1968) 
While a bit dry in spots, this film is a well researched and effective documentary. It certainly has a political agenda but is always level-headed and not shriekingly partisan as some political documentaries of today. Instead of focusing on the American combat mission, the film takes a more historical overview of Vietnam. The emphasis is on how the Vietnamese has been a constant struggle for Independence and how Ho Chi Minh is a national figure second to none in that nation. All of it leads to the central idea that the Vietnam war is (or was) an unwinnable war. de Antonio uses a wealth of different footage, most of it found footage, to get his message across and constructs a film effective in emphasizing its political message. Having seen this film years ago in a found footage class taught by experimental filmmaker Martin Arnold, it was definitely one of the more interesting pieces seen in a class focused mostly on experimental film. It doesn't quite hold up in esteem since that first viewing, mostly because of its tedious history lesson tone at times. Even with its detriments, it works and has clear parallels to the situation in Iraq and the documentaries born out of that conflict.