I don't believe that having civilian control of the military guarantees any better result or any better way of measuring success or failure. There are many examples of both methods failing or succeeding. A dictator, either military or civilian, uses intimidation and total control of the population to maintain power. When the rights of the many are suspended or taken away for the benefit of a few, when the survival of the state matters more than the individuals that inhabit it, there will always be a tendency to sacrifice personal liberties. Personal choices, by those who have the power, and those who abuse their power and personal failures usually determine the eventual outcome. It seems to me that the old adage: "Absolute power corrupts absolutely", is still very accurate more often than not. Syria is a good example of this type of government and the current war that is destroying the country. I also believe, for example, that the executive branch in America has become far too powerful and much more controlling than was ever intended by our forefathers. The role and rank of "Commander In Chief" was only meant to be used in time of war, defined by only Congress declaring a state of war exists between the USA and another country, not a President deciding when and where to use military force to support foreign policy decisions. Yes, VietNam and most wars in the period after WW II have been more politically instigated and politically controlled and politically ended or not, based on political objectives, not military considerations or consequences. Just my opinion about the current state of affairs and lack of leadership displayed by too many to count, albeit the late head of the CIA is a good example.
Semper Fi