Why do so many people feel guilty about Kiowa's death in "In the Field"?

I think that guilt is invariably connected to frustration and futility. The men wish they could have helped Kiowa but the chaos of war dictates what happens to him. In the end the men don't know who to blame so they turn their personal and collective frustration into guilt,

“When a man died, there had to be blame. Jimmy Cross understood this. You could blame the war. You could blame the idiots who made the war. You could blame Kiowa for going to it…You could blame people who were too lazy to read a newspaper, who were bored by the daily body counts, who switched channels at the mention of politics. You could blame whole nations. You could blame God. You could blame the munitions makers or Karl Marx or a trick of fate or an old man in Omaha who forgot to vote” (174).