TIL that US Marine John Kelly was the last person to be awarded 2 Medals of Honor. He ran 100 yards in advance of the front line and attacked an enemy machine gun nest, killed the gunner with a grenade, shot another man with his pistol, and returned with 8 prisoners. He was 19.

I think it is an accepted definition in the context of war, but not the only one.

From what I can tell (an NPR article/summary including an interview on of the author) Savage Continent is about the aftermath of that war. Yes people suffered greatly during and after the war, but not because of the idea that risking personal harm as part of bravery is a common notion of greatness or heroism. In fact many displays of such heroism is why the war, an untimely more suffering, ended. The medal is to commend those who exhibit great bravery and selflessness above and beyond their duty.

If you're inferring that these ideas are what propagated the war and eventually its suffering because of the aftermath, you missed the point. This war was started by a mad man who lied and abused anyone he deemed unfavorable, then tricked a country into thinking it was under attacked. The gallantry of a regular solider (not SS) was fueled by their belief that they were protecting their homeland, way of life and loved ones.

It isn't like the common soldier is blood thirsty an wants his chance to kill the enemy to "prove" himself.

"Why of course the people don't want war. Why should some poor slob on a farm want to risk his life in a war when the best he can get out of it is to come back to his farm in one piece? Naturally the common people don't want war neither in Russia, nor in England, nor for that matter in Germany. That is understood. But, after all, it is the leaders of the country who determine the policy and it is always a simple matter to drag the people along, whether it is a democracy, or a fascist dictatorship, or a parliament, or a communist dictatorship. Voice or no voice, the people can always be brought to the bidding of the leaders. That is easy. All you have to do is tell them they are being attacked, and denounce the peacemakers for lack of patriotism and exposing the country to danger. It works the same in any country." ---- Hermann Goering

/r/todayilearned Thread Link - en.wikipedia.org