I remember, very well, the Vietnam Era. I turned 18 in 1972 when the war was, finally, at long last, starting to wind down. My own husband was 18 in 1967, and was at prime draft age. (The only reason he was not drafted was because he was very nearsighted.)
During the Vietnam Era, the military was bloated with draftees. Draftees had no reason to want to be there, no incentive to apply themselves to training, except to prevent their own butts being shot off.
People who opposed the Vietnam War, including myself, were of the opinion that the war kept on going BECAUSE young men (no reason here to use gender neutral language) allowed themselves to be drafted. If the draftees would refuse to go, we reasoned incorrectly, the war would stop for lack of warm bodies to throw in front of bullets.
Of course, evading the draft was a path also fraught with peril. Yes, some men ended up in jail. Some went to Canada. Some fathered children that otherwise would not have been born. Some claimed CO status that affected their careers for the indefinite future.
By contrast, today we have an all-volunteer military. The people in the military now are folks who have chosen the career of a soldier, sailor or Marine. When one joins the military, one takes an oath to obey the Commander in Chief. Don't want to obey? Don't join.
But once that career path is chosen, the person's path is determined by the Commander in Chief and other elected officials. This goes on until they have fulfilled whatever obligation they agreed to.
(A trivial corollary would be a person choosing a career of first grade teacher. Working with 6 year old kids is part of the territory. Don't want to work with 6 year olds? Don't get a job as a first grade teacher. Yeah, I know, stupid example. But it illustrates my point. With certain jobs come certain responsibilites.)
Thus the professional military officer or enlisted man or woman is obliged to obey the Commander in Chief.
No matter how stupid, stubborn, inept and misguided that CinC might be.
The thing that makes me so sad about the current situation is that we did not learn a very important lesson from the Vietnam War. That is: Sure, Americans can go into a small country with tremendous military might. They will prevail. But... eventually the Americans have to go home. The people in that country will never leave to "go home" because HOME IS THERE. Decades after the last American left Saigon, the Vietnamese are STILL THERE.
Big, huge question: What do the common people and rational leaders in that country want? Do they want Americans to liberate them from an oppressive dictator? (eg: Germany under Hitler) If so, will the American occupation be welcome by the common people?
Instead, will the American occupation be perceived as worse than whatever Evil Dictator is there? "Yep, Mr Big might be an Evil Dictator, but he's our Evil Dictator." Would that unite various political factions in the county into the single cause of ejecting the Americans?
As for Saddam's possession of WMD and his tyranny, I submit there are plenty of other pariah nations with WMD capability who are ruled by tyrannical dictators. North Korea comes immediately to mind. We do not have the capability of invading all these countries and toppling all the tyrants of the world.
My personal opinion is that the invasion of Afghanistan was justified. The invasion of Iraq was not. Had GWB concentrated his efforts on Afghanistan, we would have nabbed Bin Laden by now, and the whole area would have been in much better shape.