You neglect the fact that law abiding people use guns to prevent violent crimes against themselves and others keeping people from dying (about a million times a year). The media is so lopsided that they never report stories of "the good guy with a gun" stopping violent attacks- would scuttle their motives to convince people that taking a means of defense away from law abiding people would make us all safer from those who aren't law abiding. There are raw FBI data you could analyze, studies by Lott and others that show from statistics and reality that criminals kill people, not guns. It wasn't long ago that we took violent people out of society, "locked them up and threw away the key" so to speak, but now we have to show more compassion to the murderer than the murderer showed his or her victims. Oh, lethal injection might hurt, then we just can't use the death penalty authorized by a court of law, however, the death penalty imposed by the killer not authorized by law still stands!
Regarding WWII, there was an early recognition of what was happening to the Jews, Gypsies, homosexuals and handicapped people (to the tune of 10 million victims), but it was politically expedient to ignore it and dismiss the reports of it happening.
And the guerilla war in Viet Nam was executed in order to hold off an overwhelming US military, the communist factions behind the tactic had no qualms about the collateral damage to 1.3 million people to accomplish their objectives. Talk to any Nam vet who saw combat, and you'll know a lot of our 58,000 dead died because our politicians wanted to fight a polite war. If they would have been allowed to fight to win, the casualty count would have been drastically lower. As it was, according to Soviet documents recovered when the USSR fell, all our men did was stop the Domino Theory from becoming reality, no small accomplishment.