Secession and General Lee
Within four months of the 1860 presidential election of Republican Abraham Lincoln, South Carolina, Mississippi, Florida, Alabama, Georgia, Louisiana, and Texas seceded from the Union. On April 12, 1861, Confederate forces attacked and captured Fort Sumter in Charleston, South Carolina. Three days later, President Lincoln called up 75,000 militiamen.
As Colonel of the 2nd Cavalry, Robert E. Lee enjoyed a celebrated reputation. Acting at the behest of his friend President Lincoln, Francis Preston Blair offered command of the Union Army to Lee in a meeting in Blair House. Knowing that the secession of his native Virginia was imminent, Lee declined the offer and resigned his commission in the U.S. Army, taking command of the Confederate Army of Northern Virginia two days later.
Interestingly, Lee had no particular attachment to slavery, and he was powerfully in favor of the Union and the Constitution. But his attachment to his native state was even stronger.