23rd of 45 excerpts from Lincoln by David Herbert Donald:
Lincoln's July 4, 1861, message to a special session of Congress offered a full explanation of the course he had pursued in the Sumter crisis, blamed the Southerners for beginning the conflict, and defended the subsequent actions he had taken to sustain the Union. Valuable as history, the message was more significant as prediction. Taken together with his proclamation of April 15, it clearly defined Lincoln's view of the war and explained how he intended to prosecute it.
The conflict, he consistently maintained, was not a war between the government of the United States and that of the Confederate States of America. So to define it would acknowledge that the Union was not a perpetual one and the secession was constitutional. This Lincoln could not even tacitly admit. Throughout the next four years he sustained the legal fiction that the war as an "insurrection" of individuals in the Southern states who joined in "combinations too powerful to be suppressed by the ordinary course of judicial proceedings." Though he sometimes referred to the conflict as a civil war, he usually called it a "rebellion" -- a term he employed more than four hundred times in his messages and letters. . . .
In the years ahead Lincoln was not always able to keep to the purest formulation of his interpretation of the war. Had he done so, captured Confederate soldiers would have been treated as criminals and captured Southern seamen as pirates. This, as Jefferson David bluntly warned him, could only lead to retaliation. Without any public announcement, the Lincoln administration modified its position. Throughout the war captured Confederate soldiers and sailors were confined in prison camps -- camps that were, in both the Union and the Confederacy, overcrowded and squalid beyond belief but were nevertheless preferable to the common jails where these prisoners might have been sent. . . .
Lincoln's July 1861 message, together with his proclamations, also made it clear that he considered the prosecution of the war primarily a function of the Chief Executive, to be carried out with minimal interference from other branches of government and without excessive respect to constitutional niceties protecting individual rights. To carry out his duties as commander-in-chief, he believed that he could exercise powers normally reserved to the legislative branch of government.