All military deaths, for all causes, totaled about 365,000 of the Union, and 135,000 for the confederacy (as per D.O.D.). Add in your 50,000 civilian "casualties" and you are just barely at half of your earlier estimate. And that includes your ever-widening definition of "wanton death."
Since you have divined that every death in the war was unjustified, then what was the purpose of describing them as "wanton." Like Rush says, "Words mean something." "Wanton" has a particular definition and you seem to use it to make emotional hyperbole. Your usage is "gratuitous."
I see it another way. Every death in the Civil War helped ensure a similar war would never again happen. Despite some of the more outrageous statements by your compatriots, indicating the the AZTLAN war is on the way and the second WBTS is imminent, the fact of the matter is that such thinking is fantasy time.
The total figure I have for officially recorded deaths says 624,726 for military deaths of all type on both sides combined. Since the numbers are incomplete most reasonable estimates place the total closer to 700,000, give or take. Add 50,000 confederate civilians directly killed for 750,000. We can up things beyond that as well by counting union and border state civilians and civilians who were indirectly killed by displacement. I don't believe there is an exact figure on that anywhere so it's anybody's guess as to how many. Suffice to say, 800,000 deaths is not at all out of the picture. And yes, they were WANTON as they resulted directly from an unnecessary and needless war.
His position is reasonable, in that Lincoln had no warrant to make war on the Southern States that had withdrawn from the Union.
You will recall that Tennessee, Missouri, and Virginia had all rejected secession initially. In the case of Virginia, rejection was by the secession convention called specifically to consider the question. That should tell you something about what it took to push Virginia and Tennessee over the edge. It was Lincoln's call for troops to go kill people in the other States.
Lincoln couldn't argue "insurrection", since there was no "uprising" or "rebellion" or similar civil disorder certified to him by the governors of the Southern States. Gov. Sam Houston of Texas even refused Lincoln's solicitation of a certification, with its offer of 75,000 men stapled to it, and certified the opposite by his actions: that Texas's secession, like the secession acts of each of the other States, was a lawful act of the entire People of Texas, and that they had acted wholly within their powers to make the decision to secede.
Lincoln, absent a declaration of war by the Congress, without any true certification of rebellion or insurrection, had no right to proceed to war. We might argue, conditionally, about what might have been required for him to wage war constitutionally on the newly-estranged States, had Congress sat to consider the question.
But the bottom line is that Congress did not sit to consider secession, Lincoln did not recall the House to consider articles of war, he did not seek the advice and consent of the Senate. Instead, he undertook a clandestine and left-handed decision for war. War was his policy, undertaken as soon as the House adjourned. He did so wilfully and extraconstitutionally, from the standpoint of the United States Constitution and the U.S. political system, and as an alien aggressor from the POV of the seceding States.
Thus GOPcapitalist has made a strong case, that Lincoln's responsibility -- which Lincoln himself gave voice on at least one occasion -- for the WBTS was very grave, and that having no warrant to wage it, his actions were wanton and burdened accordingly.