Chuck Hagel's departure from his post as U.S. defense secretary has been attributed to his failure to fit in with the Obama Cabinet's crowd. Among his other reported deficiencies was that he was only a sergeant in Vietnam, twice wounded.
A twice-wounded veteran, I should think, would make him a rare specimen in a Washington packed full of senators and congressmen, and State Department and National Security Council staff who assume that they know more about war than Carl von Clausewitz, and unwounded but heavily decorated generals eager to get back to showing their stuff, as in the wars in Iraq and Afghanistan.
(As I have noted before, the most celebrated of those, David Petraeus, when he resigned from the army, was entitled to display more than 50 items of military adornment up one side and down the other of his chest, none of them an award for wounds suffered in combat. One understands why a former sergeant may be thought a social embarrassment, especially if he calls himself "Chuck.")