To "win" a war you must have specific and measurable goals. If your politicians start a war but cannot articulate such goals, you're going to lose. They'll assure you they will win, but they've already lost. They are bad at their jobs, why did you hire these morons?
I can't believe I had to scroll down to see this. Victory always flows down; you can have the most badass of technical equipment or cunning tactical victories in the field, then still quite enthusiastically lose the war, due to bad strategy or even the original political goals of conflict.
Or because the political goals were impossible or - almost breathtaking that this state can even exist - because the goals are entirely absent. Incidentally, having a "rotating roster" of different political goals probably counts as something worse than "absent", due to the illusory impression that it gives of "someone deciding something".