On April 12, at 3:20 AM, after a final effort to have the Union garrison surrender, Col. Robert Chestnut, CSA, notified Major Robert Anderson, USA that in one hour the batteries commanded by Brigadier General Pierre G. T. Beauregard would open fire. Anderson, who had been a professor of Artillery at West Point, aware of the consequences of this, was deeply moved by the declaration. As would happen many times again over the next four years, the embattled leaders knew each other well. Beauregard, back at West Point, had been Anderson's assistant. After a 34-hour bombardment, Major Robert Anderson surrendered the fort.