My Lai is often portrayed as the symbol of US misconduct during the Vietnam conflict. Was there other My Lai-style massacres before or after the event which comparatively recieve little attention, and if so how widespread were they? Is the Vietnam stereotype of constant misconduct - summed up by Walter in The Big Lebowski "Smokey this is not 'Nam, this is bowling. There are rules" - true?
I've touched on this topic before, based on what caused atrocities to happen in the first place: http://www.reddit.com/r/AskHistorians/comments/1dih4r/did_us_forces_commonly_kill_intentionally/c9qn064
Due to the nature of the conflict, the inexperience of the men involved and the conventional strategy chosen - atrocities, the killing of innocent civilians, did happen. Was the killing of civilians widespread throughout the conflict? One could definitely argue that it was, but not on the same scale as My Lai which was the exception rather than the norm. However, let it be clear: Not every US soldier witnessed atrocities or committed them. The war in Vietnam was not on the scale of atrocities as committed the Eastern Front in WWII in which ideology and perceptions of race led the Germans on a war of extermination. No one can deny that atrocities happened during the Vietnam War, but one should not be so prone as to jump on the "imperialist genocide" wagon.
It is interesting to note that at the time the My Lai massacre was occurring, another massacre was occurring at the same time at Son Thang nearby. Another case of atrocities on the same scale as My Lai is the infamous Tiger Force, a task force from the 101st Airborne Division which during a period in 1967 committed a series of atrocities against civilians which is simply unheard of in the context of the Vietnam War.
One issue that historians and journalists working with atrocities in Vietnam face is that it is very difficult to get any sort of reliable numbers for how widespread it really was. Sometimes, we encounter claims of atrocities which never occurred. Sometimes we encounter claims of atrocities which were denied by media or public figures at the time but that historians and investigative journalists many, many years down the road actually manages to confirm. I've previously written on the infamous "Winter Soldier" documentary here where I touch on the same subject.
To quickly sum it up: Did atrocities happen in South Vietnam? Yes. Were all of them like My Lai? No, it was the exception rather than the norm.