Of course, as soon as the facts were known he was restored to his command with an ample apology, but his preparations for the advance against Corinth had been seriously interrupted and it was some time before he again had the work in hand. Nevertheless, within five weeks of the surrender of Fort Donelson, he was headed toward Mississippi with over 30,000 men, having arranged with General Buell to follow and support him with his army of 40,000, the combined forces being amply sufficient to overpower the Confederates who were guarding Corinth. This vast superiority, however, probably served to put Grant off his guard, for on March 16, 1862, his advance under General Sherman reached Pittsburg Landing, not far from Corinth, and encamped there without taking the precaution to intrench. Sherman reported on April 5th that he had no fear of being attacked and Grant, who had been injured the day before by the fall of his horse and was still on crutches, remained some distance in the rear, feeling confident that there would be no serious fighting for several days. But the Union commander, who had studied his opponents with such good results at Fort Donelson, made a terrible mistake in failing to do so on this occasion, for he knew, or ought to have known, that General Albert Sidney Johnston and General Beauregard, the Confederate commanders were bold and energetic officers who were well advised of the military situation and ready to take advantage of every opportunity. Indeed, their sharp eyes had already noted the gap between Grant's and Buell's armies and at the moment Sherman was penning his dispatch to his superior, informing him that all was well, a force of 40,000 men was preparing to crush his unprotected advance guard before Buell could reach the field. It was Sunday morning, April 6, 1862, when the ominous sound of firing in the direction of Shiloh Church smote Grant's ears. For a few moments he could not believe that it indicated a serious attack, but the roar of heavy guns soon convinced him that a desperate battle had begun and, directing his orderlies to lift him into the saddle, he dashed to the nearest boat landing and proceeded to the front with all possible speed. Before he reached the ground, however, the Confederates had driven the Union outposts from the field in frightful disorder and were hurling themselves with ferocious energy upon those who still held fast. The surprise had been well-nigh complete and the first rush of the gray infantry carried everything before it, leaving the foremost Union camp in their hands. Indeed, for a time the Federal army was not much more than a disorganized mob, completely bewildered by the shock of battle, and thousands of men blindly sought refuge in the rear, heedless of their officers who, with a few exceptions, strove valiantly to organize an effective defense.