President Lincoln took office on 4 March 1861. At that time, seven states from the Deep South had seceded from the Union, but four other slave states (Virginia, Arkansas, North Carolina and Tennessee) had voted to remain. In mid April Confederate forces fired on Fort Sumter, but the bigger economic threat was converting southern ports to duty-free zones. This would have put Northern Ports out of business and deprived the federal government of a primary source of revenue.
In response, Lincoln called for northern troops to put down (i.e., invade) the rebellious states. This unprecedented action outraged the remaining southern states and caused them, led by Virginia, to secede in short order. Virginia was now the most populous and important state in the Confederacy, which quickly moved its capital to Richmond.
What if Lincoln had not taken this precipitous step and Virginia had stayed in the Union? Without it, the Confederacy would have consisted of a collection of backward agricultural states with little manufacturing capacity, almost entirely dependent on imports from foreign countries. Instead of invading these states, Lincoln could have ordered a trade embargo and blockaded their ports. These actions would have been ruinous to the seceding states and, without Virginia's manpower and manufacturing capacity, they would have been forced to capitulate and rejoin the Union.
What do you think of this scenario? Could we have avoided the carnage and destruction of the Civil War if more moderate steps had been taken? Slavery was already a dying institution. (It had completely disappeared in the Western Hemisphere by 1888.) Was it worth 600,000 lives to end it 25 years sooner?