Cannons and a stone plaque at the Shiloh National Military Park, Tennessee.

In February 1862, General Ulysses S. Grant had captured Forts Henry and Donelson, opening up central Tennessee to the Union and making him a national hero with his insistence on “unconditional surrender.” Grant advanced his army along the Tennessee River to an isolated area just north of that state’s borders with Mississippi and Alabama. Another army, commanded by General Don Carlos Buell, had been ordered to join Grant and they would both then advance to capture the key rail junction at Corinth, Mississippi, less than 25 miles to the southwest.

The Confederate commander, Albert Sidney Johnston who at the time was regarded as the new nation’s best general, sought to disrupt the Union plans and regain the initiative for the South. His Army of Mississippi was concentrated around Corinth and he planned a surprise advance and attack on Grant before Buell could join him. Johnston’s scouts had made him aware that Grant, obsessed with advancing, had left his encampment unfortified and vulnerable.

The Confederates set forth from Corinth on April 3, planning to attack on the 4th, well before the arrival of Buell. However, a torrential rain turned the already primitive roads and trails into a morass of mud. During the Civil War, it was difficult in the best of conditions to get an army to its destination on time. Now it proved impossible and took three days for Johnston to advance the 23 miles. The result was that while he succeeded in initially catching Grant by surprise on April 6, Buell was to arrive in time to help launch a Union counterattack the next day.

The initial assault early on the morning of the 6th seemed like it would yield a Confederate victory. A soldier of the 6th Arkansas, Henry Morton Stanley, who ten years later was to “discover” Dr. David Livingstone in Africa, recalled:

Those savage yells, and the sight of thousands of racing figures coming towards them, discomfited the blue-coats; and when we arrived upon the place where they had stood, they had vanished. Then we caught sight of their beautiful array of tents, before which they had made their stand, after being roused from their Sunday-morning sleep, and huddled into line, at hearing their pickets challenge our skirmishers. The half-dressed dead and wounded showed what a surprise our attack had been.

But though some Union units fled, others made a stand, slowing the Confederate advance. The topography of the battlefield also worked against the Rebels, as it both funneled their advance into a narrower front and required them to cross several deep ravines in the face of Union fire, including from gunboats on the river. The Confederates became more disorganized, a confusion compounded by the mortal wounding of General Johnston. The battlefield eventually quieted as darkness fell.

What was it like that night? Here are the recollections of a Union soldier of the 9th Indiana; Ambrose Bierce, author of The Devil’s Dictionary and An Occurrence at Owl Creek Bridge (made into a famous “Twilight Zone” episode), who was to disappear in Mexico in 1913 during its revolution:

The night was now black-dark; as is usual after a battle it had begun to rain. Still we moved, we were being put into position by somebody. Inch by inch we crept along, treading on one another’s heels by way of keeping together . . . When the men had pressed so closely together that they could advance no farther they stood stock-still . . . In this position many fell asleep . . . Very often we struck our feet against the dead; more frequently against those who still had spirit enough to resent it with a moan . . . Some had sense enough to ask in their weak way for water. Absurd! Their clothes were soaken, their hair dank; . . . Besides none of us had any water. There was plenty coming, though, for before midnight a thunderstorm broke upon us with great violence. The rain, which has for hours been a dull drizzle, fell with a copiousness that stifled us; we moved in running water up to our ankles.

Grant may have failed to take precautions to protect his position but once the battle started his customary calmness and imperturbability came into play. He refused to take the advice of some of his officers to withdraw the army, directed the establishment of a new defensive line, and once he knew Buell’s army would be available on the 7th, determined to take the offensive. With daylight, Grant ordered an advance and much of the ground lost by the Union in the first day was recovered and the Confederates withdrew back to Corinth, their goal not attained. Grant received much criticism for leaving his army so exposed to attack but managed to survive, fortunately for the Union. Henry Morton Stanley was captured in the Union counterattack, ending his career as a Confederate soldier, though he was to enlist and briefly serve in the Union Army.

The casualty toll of Shiloh was a shock to both sides. Until then, the bloodiest battle of the war had been Bull Run in July 1861 where the combined dead and wounded amounted to 3,500. For the entire Civil War until April 6 about 10,000 had been killed or wounded. The dead and wounded in the two days of Shiloh totaled just under 20,000. It was a harbinger of worse to come.

You can learn more about the Battle of Shiloh watching this video from the American Battlefield Trust.