What was the date when 4 states left the union after the attack at fort Sumter?

Answer 1

The four upper south states did not all secede on the same day. The day after the attack on Fort Sumter, April 15, 1861, Lincoln called for 75,000 troops to help "suppress the rebellion", and assigned a quota of part of that 75,000 to each state, including the four states of the upper south. That put those four states to the decision of whether to help make war on their relatives and neighbors in adjoining states, or to throw in with them. Each of the four states had to work its way through whatever political framework had been created for making the decision on whether to secede. Virginia, for instance, had a Convention to decide the issue which had been meeting since February 13, after the seven states which were the first to secede had formed the Confederate States of America on February 4. The Virginia Convention had actually voted against secession on April 4, but then eight days later the attack on Sumter began, and on April 15 came Lincoln's call for troops from Virginia. Since the Virginia Convention was already meeting and able to decide the issue, they were able to vote to secede on April 17. It took North Carolina a month longer, because a statewide referendum had to be organized to let all the eligible voters vote on the issue, so North Carolina did not secede until May 20.