"The plain, uncontrovertable fact is that the Confederate States of America was formed and went to war and fought for four years for the right to keep other human beings in bondage to maintain the southern slave-based economy . . . ."

Not so simple, Greg. First of all, the slaveholding states did in fact fear that the newly elected Abraham Lincoln was a closet abolitionist who would destroy slavery, despite his protestations to the contrary. South Carolina and then other Deep South states did secede based to a considerable degree upon these fears (see the Declarations of the Causes of the Seceding States for S. Carolina, Texas, Georgia and Mississippi, which can be read here). Other states followed, though four Upper South states (Virginia, North Carolina, Tennessee, and Arkansas) remained in the Union, only seceding when Lincoln called up troops to put down the rebellion (NOT to free the slaves). Historians James G. Randall and David Donald have argued that the choice of the military option by Lincoln "served in one flash to alienate that whole mass of Union sentiment which, while not pro-Lincoln, was nevertheless antisecessionist and constituted Lincoln's best chance of saving the Union without war." Other slave states (Kentucky, in particular) stayed in the Union, despite the divided loyalties of their populations. So, some slave states left the Union because of the perceived threat of abolitionism with a Republican government; others left (it has been argued) in response to the Northern military threat against other Southern states; while other slave states remained in the Union. At the outbreak of hostilities, no one could have known that the end result (perhaps the only positive result of the war) would be the complete dismantling of the slave regime in the the Southern United States.

" . . . which regional economic system benefited the entire southern population not just the big plantation owners."

Absolutely false, the exact opposite of the truth. It should be painfully obvious that an agrarian economic system in which a small minority of wealthy slaveholders controlled the best agricultural land would disadvantage the majority.

"Its also apparently difficult for some people to realize that in many (most?) instances soldiers have little or no accutate idea of what they are fighting for. Lots of grunts in Iraq believe the fairytale that they're "defending America". They have to rationalize their participation somehow . . . ."

Not a very good analogy. The North invaded the South. If anything, the 'insurgents' (Iraqis, both Sunni and Shiite, NOT foreign fighters) are analogous to poor whites who fought for the CSA.

Back to the subject:

Yes, there were some blacks who fought for the Confederacy. At least a few hundred, perhaps a few thousand. There was also a vigorous debate within the South over the question of emancipation in exchange for military service. Some Southerners rightly saw that this would lead to the destruction of slavery, and therefore opposed it. Others argued that the preservation of Southern independence was far more important than defending an institution that anyway was doomed if the South was defeated.