Heroism: what defines it?

I was thinking about some of the recent criticisms of John Kerry; perhaps some of it is undeserved. I keep hearing about how the left, for decades having demonized the Vietnam War, are now suddenly praising it and producing a war hero from it--John Kerry. Also, the left supposedly is taking the Iraq war and trying to portray it as they first portrayed Vietnam. So I was thinking about what makes men war heroes. Does the justification of the war effect the heroism of the soldier? If it turns out (even though it won't) that the Iraq War was completely unjust, will that mean that none of the men who fought courageously in battle are heroes? Yes and no, I think. If the United States sent troops over to India and ordered men to start killing Dalits ("Untouchables") for no reason, I believe the soldier who follows those orders is not innocent; both government and soldier should be held accountable. There's something different about Iraq and Vietnam, though. Obviously, people hold strong views for and against both wars. But I would never say that a soldier who acted courageously in combat in Vietnam is not a hero because I disagreed with the war. Even though the Democrats opposed the Vietnam War, that doesn't mean (in principle) that it's inconsistent for them to recognize a hero from that war. There. It took my thoughts forever to coalesce into a main point.

That's my one concern with the concept that Republicans seem to be using: that if you are opposed to a war you can't recognize a hero from that war. But......(now let's get on to the meaty specifics)

If John Kerry represented the views and intentions of the Democratic party of the 1960's, then it is wrong for those same Dems to proclaim Kerry a war hero now. John Kerry undermined the war effort to the effect that it caused more American deaths in Vietnam (because of reduced support at home for the war), emboldened the Vietnamese holding POWs and demoralized those POWs (including Senator John McCain). If you didn't support a soldier when he was in combat, you can't praise him for being a war hero 30 years later.

There are two things I want to say about the atrocities John Kerry claimed he committed.

1. if he did commit them, he is not a war hero, regardless of anything else courageous he might have done.
2. these atrocities have been hotly contested and denied by many of Kerry's fellow soldiers. Why would he lies about these things, if not to undermine the war effort and profit himself personally?

Even Kerry's Purple Hearts have been shrouded in controversy; one "wound" was treated with a BandAid, and Kerry's story did not fit the one given by the men who were with him.

Thus, I have come to some conclusions. Either Kerry committed atrocities, and he is not a war hero, or he did not and he is a liar, and thus casts doubt on his heroics.