In the early morning hours, after he became convinced that federal ships were approaching Charleston to relieve Fort Sumter, General Beauregard sent members of his staff to again request immediate surrender of Major Anderson. He also gave them authority, if refused, to inform Anderson that he would order his batteries to open fire "in one hour from this time." This they did, at 3:20 a.m., and immediately left the fort. Fire commenced on Sumter as promised, one hour later. (By John Osborne)
Benson J. Lossing, Pictorial History of the Civil War in the United States of America (Mansfield, OH: Estill & Co., 1866), 319-320.