One of the most famous of all surprises in military history is Pearl Harbor, where Japanese planes attacked the U.S. Pacific Fleet based in Hawaii. The attack on December 7, 1941, was indeed a surprise, with bombs dropping out of a clear blue sky. Shiloh is another well-known example of a supposed surprise attack. On the morning of April 6, 1862, the Confederate Army of the Mississippi under Johnston launched an attack on Maj. Gen. Grant’s Army of the Tennessee near Pittsburg Landing. One author has even gone so far as to call it the Pearl Harbor of the Civil War. In actuality, Shiloh was not all that much of a surprise.

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The assertion of surprise came initially from contemporary newspaper columns that described Union soldiers being bayoneted in their tents as they slept. The most famous account came from Whitelaw Reid, a newspaper correspondent for the Cincinnati Gazette. But Reid was nowhere near Shiloh when the Confederates attacked, and he actually penned his nearly 15,000-word opus from miles away.

The idea that Reid perpetuated and that is still commonly believed today is that the Federals had no idea that the enemy was so near. Nothing could be further from the truth. For days before April 6, minor skirmishing took place. Both sides routinely took prisoners in the days leading up to the battle. The rank and file in the Union army knew Confederates were out there — they just did not know in what strength.

The problem lay with the Federal commanders. Ordered not to bring on an engagement and convinced they would have to march to Corinth, Miss., to fight the bulk of the Confederate army, the Union leadership did not properly utilize the intelligence gained from the common soldiers on the front lines. Grant was not about to go looking for a fight in early April, certainly not before reinforcements arrived from Nashville in the form of the Army of the Ohio, and certainly not without orders from his superior, Maj. Gen. Henry W. Halleck.

Thus Grant ordered his frontline division commanders Sherman and Prentiss not to spark a fight, and they made sure their soldiers understood that directive. They sent orders reinforcing Grant’s concern down the line and refused to act on intelligence coming up through the ranks.

As a result, not wanting to prematurely begin a battle, Federal skirmishers and pickets continually withdrew as the Confederates probed forward. Perhaps Sherman said it best when he noted in his report, On Saturday the enemy’s cavalry was again very bold, coming well down to our front, yet I did not believe that he designed anything but a strong demonstration.

The lower echelon leadership was not all that convinced the fight would take place at Corinth, however. For days, brigade and regimental commanders had witnessed Confederates near their camps. Several patrols even went forward, but no major Confederate units were encountered.

Finally, on the night of April 5, one Union brigade commander took matters into his own hands. Sending out a patrol without authorization, Colonel Everett Peabody located the Confederate army at dawn on April 6. His tiny reconnaissance found the advance skirmishers of the Southern force less than a mile from the Union front. The Confederates promptly attacked, and the Battle of Shiloh began.

Because of Peabody’s patrol, however, the Confederate advance was unmasked earlier than intended and farther out from the Union camps than projected. The resulting delay in the Confederate assault on the Union camps allowed the Army of the Tennessee to mobilize. Because of the warning, every single Union unit on the field met the Confederate assault coming from Corinth south, or in advance of, their camps. Peabody’s patrol warned the army and thus prevented total tactical surprise at Shiloh.

Benjamin Prentiss was the hero of Shiloh.

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