The issue of the size and composition of a ground component of an invasion and the overall size of our Army and Marine Corps will be based on the just unofficially concluded Iraq War as a point of evidence. Both sides will use it. This is my take on it.
First of all, the size of the invasion force and whether it constituted overwhelming force is contested. The size of the invasion force was debated long before the war. Some favored a tiny force basically mimicking the Afghanistan campaign of special operations forces helping locals with a small amount of conventional forces to spearhead the advance. The inside-out strategy of heading for Baghdad first in an airborne attack was an extreme form of this strategy. Others wanted a near-replay of Desert Storm. We ended up with a British division, a large American heavy division, a large American air assault division, a huge Marine "division," and a couple parachute brigades. Plus Military Police and separate line battalions, presumably for security purposes. I wonder if in the battle between Franks and Rumsfeld (ok, I am assuming they tugged in the opposite direction for how many troops could go), at some point Rumsfeld put a cap on the invasion force, saying no more than three American divisions could be sent to Kuwait. (I'm also discounting 4th ID's cancelled Turkish front. I never considered it vital for the invasion and possibly counter-productive) If so, did the uniformed Pentagon then deploy enough Marines for more than two divisions into one MEF; put four heavy brigades under one Army division, and beef up the air assault division to get around that limit? (I'm assuming it was beefed up since it is often said it has 20,000 troops in it) And then the separate brigades and battalions don't count. Nor did the MPs. If so, we must make sure that we don't think we can replicate this war with three American divisions and one allied division as the heart of the invasion force. This certainly was a cakewalk by any stretch of the term but it was achieved with an iron fist and not a small force. We really had 2+ Marines divisions, 3+ Army divisions, and 1 British division. Again, I would rather have added a second Army heavy division in place of a Marine division-equivalent to guard against a setback in the main armored drive to Baghdad, but since we did not face such a setback I can't complain too much—I just hope the next time, should another war come, we send more heavy armor to provide us with a margin of error.
So, it is established to my satisfaction that we had overwhelming ground power. The second question we must ask is whether we can do this again in other circumstances. Yes, our superb air power could do this again in another war, but I think we must be very careful in assuming this size force could win as easily in a different country. We had overwhelming ground power in Iraq because we could keep most of our ground combat power up front. Despite all the press the supply line attacks received, they were gnats. They did not represent a true guerrilla war by the Iraqis angry with our invasion. We really did rely on the Iraqis wanting Saddam out so badly that they would not think of us as invaders. Had the Iraqi people felt we were invaders, like any other invading army, we would have had to strip substantial combat forces to garrison our rear areas. (Then, my idea of supplying through Jordan would have reduced the need for this by avoiding supply lines through populated areas) This restricts what our military can do since we invade a unified, hostile state at our peril. Firepower and speed can replace numbers but only if we do not face a hostile population. Police work is labor intensive. Keep that in mind when people suggest who should be next. If we face a united enemy, we may need years of work to undermine their loyalty to the regime to prepare the battlefield. Otherwise, we'll need more troops from our own resources or from allies.
So, like any other war, this war may or may not be a prototype of our future wars. They are all different and so it would be better to get used to that now.
Having established (again, to my satisfaction) that the overwhelming force used in Iraq may or may not be overwhelming in other circumstances, it is clear to me that the Iraq War should not lead to the conclusion that we can cut a couple Army divisions and scrap a Marine Expeditionary Force, placing all our trust in our awesome air power. We need at least as many troops as we have today at a barely acceptable minimum. Shoot, we need 40,000 more just to man the force structure. And we may need more support troops on active duty just in case rather than putting so many in the reserves. But most important, we must figure out what type of troops should be in our military. Transformation is supposed to create the light and lethal Objective Force. The Crusader is gone. That I don't mind, since Paladin is damned good. What does bother me is the impending demise of the Abrams and Bradley in a couple decades with nothing similar to replace them planned. The Stryker Brigade Combat Teams are the prototype of the lighter Army of the future, with the Future Combat System yet to be developed not much heavier than the Strykers, yet far more lethal and far more survivable. Yeah, right.
The Iraq War showed the value of our heavy armor in no uncertain terms. They mostly shrugged off RPG hits and kept going, smashing anything in their way. Even our lighter forces needed Abrams tanks. The Marines adopted them after Desert Storm. We airlifted some in to 173rd AB brigade this war. We left tanks to back up our paratroopers and air assault troops in city combat as the rest of 3rd ID marched north. Nor did time constraints prevent us from getting lots of heavy armor to the war. One reason for wanting lighter armor is to be able to airlift them into a war to repel an invasion with little notice. How often will this happen? I'm glad we didn't airlift a bunch of light stuff in record time back in September 2002 and then just waited for March 2003 to start the war because we thought heavy armor was not deployable. We had the time, sent our heavy armor, and reaped the benefit of this "Cold War" relic on the battlefield.
This war, far from being an argument for lightening our Army, argues for heavying up our light forces. Sure, we can still experiment with the Stryker brigades, since technology may yet make heavy armor obsolete (but we've heard that before). But for the near term, listen to what we learned in the streets of Iraq. The Abrams/Bradley team is awesome. Attach a tank battalion or a tank heavy task force to each of our light brigades. Perhaps they can be National Guard separate battalions for the most part. Give them to the light infantry, paratrooper, and air assault divisions. Depending on the war, they can be left behind or sent along as appropriate. Then, our spearhead heavy divisions won't need to strip armor to support supply line battles or urban combat. It sure worked for us in World War II when every American "infantry" division had a tank battalion and a tank destroyer battalion attached—making them the equivalent of German armored infantry divisions.
For the ground component of a joint force, heavy armor rules for now.
[NOTE: This is from the former Defense Issues category from my original blog.]