10 o'clock
Fortune , which had played a game with Grant at Donelson , played a far greater one with him on the far greater field of Shiloh . The red dawn of Shiloh , when Johnston was sweeping his army before him , had found him at Savannah far from the field of battle . The hardy and vigorous Nelson had arrived there in the night with Buell 's vanguard , and Grant had ordered it to march at speed the next day to join his own army . But he , himself , did not reach the field of Shiloh until 10 o'clock , when the fiercest battle yet known on the American continent had been raging for several hours . Grant and his staff , as they rode away from his headquarters , heard the booming of cannon in the direction of Shiloh . Some of them thought it was a mere skirmish , but it came continuously , like rolling thunder , and their trained ears told them that it rose from a line miles in length . One seeks to penetrate the mind of a commanding general at such a time , and see what his feelings were .