Many stay home. In a war with 500,000 peak combatants, most American males were not drafted whether they had a deferment or not.
I am not going to the ghetto, so I can't support the war on Poverty?
I am not going to Afghanistan, so I cannot support the war on terror.
Many were eligible for the draft and did not get drafted. My father had a deferment since he was in college at the time (born in 1951 - wasn't eligible for the draft until '69). With the birthday lottery system, his "number" each year still would not have been caused him to be drafted before the war was over.
So my dad - who by some freakish definition "dodged" his duty by not volunteering for combat - still managed to raise two young conservatives, one of whom HAS volunteered for military service in the midst of the war on terror. You don't have to serve in a combat unit, or serve in the military at all, to support a war or support the people fighting it.