President Lincoln's twenty day grace period for the rebellion to "disperse" expires
On April 15, 1861, following the firing on Fort Sumter, President Lincoln had published an executive proclamation ordering that those in rebellion "disperse and retire peacebly to their respective abodes, within twenty days from this date." This day marked the expiry of that period. (By John Osborne)
Source Citation
"The Great Rebellion," New York Times, May 5, 1861.