I can't find the exact quote you are refering to but here are a few that come close...
Older men declare war. But it is youth that must fight and die. -- Herbert Clark Hoover
I hate those men who would send into war youth to fight and die for them; the pride and cowardice of those old men, making their wars that boys must die. -- Mary Roberts Rinehart
I'm fed up to the ears with old men dreaming up wars for young men to die in. -- George McGovern