From Wikipedia
Between the years 1849 and 1865, events that took place in the United States included the American Civil War and the turbulent years leading up to it, during which occurred many events that were critical in its origins.
On April 12, 1861, after President Lincoln refused to give up Fort Sumter,
the federal base in the harbor of Charleston, South Carolina, the new
Confederate government under President Jefferson Davis ordered General P.G.T. Beauregard to open fire on the fort.
It fell two days later, without casualty, spreading the flames of war
across America. immediately, rallies were held in every town and city,
north and south, demanding war. Lincoln called for troops to retake
lost federal property, which meant an invasion of the South. In
response, four more states seceded: Virginia (April 17, 1861), Arkansas, (May 6, 1861), Tennessee (May 7, 1861), and North Carolina (May 20, 1861). The four remaining slave states, Maryland, Delaware, Missouri, and Kentucky, under heavy pressure from the Federal government did not secede; Kentucky tried, and failed, to remain neutral.
Each side had its relative strengths and weaknesses. The North had a
larger population and a far larger industrial base and transportation
system. It would be a defensive war for the South and an offensive one
for the North, and the South could count on its huge geography, and an
unhealthy climate, to prevent an invasion. In order for the North to
emerge victorious, it would have to conquer and occupy the Confederate
States of America. The South, on the other hand, only had to keep the
North at bay until the Northern public lost the will to fight. The
Confederacy adopted a military strategy designed to hold their
territory together, gain worldwide recognition, and inflict so much
punishment on invaders that the North would grow weary of the war and
negotiate a peace treaty that would recognize the independence of the
CSA. The only point of seizing Washington, or invading the North
(besides plunder) was to shock Yankees into realizing they could not
win. The Confederacy moved its capital from a safe location in Montgomery, Alabama, to the more cosmopolitan city of Richmond, Virginia,
only 100 miles from the enemy capital in Washington. Richmond was
heavily exposed, and at the end of a long supply line; much of the
Confederacy's manpower was dedicated to its defense. The North had far
greater potential advantages, but it would take a year or two to
mobilize them or warfare. Meanwhile, everyone expected a short war.