The attack on my forces has been very spirited from early this morning. The appearance of fresh troops in the field now would have a powerful effect, both by inspiring our men and disheartening the enemy.
- Major General Ulysses S. Grant to Brigadier General William "Bull" Nelson, Commanding Officer Advance Forces of the Army of the Ohio
The Battle of Shiloh erupted on the morning of April 6,1862 when the Confederate Army of Mississippi launched a powerful assault against Grant's Army of the Tennessee positioned near Shiloh Church. Federal troops rallied after the initial surprise, conducting a fighting withdraw toward their base at Pittsburgh Landing where they were supported by Navy gunboats on the Tennessee River.
Grant's battered army was reinforced that evening by the lead elements of the Army of the Ohio, commanded by Major General Don Carlos Buell. The army consisted of four infantry divisions numbering around 20,000 men. Buell's force had advanced west from Nashville to combine with Grant to conduct joint operations toward Corinth, Mississippi and to strike at Confederate communications and transportation lines. The arrival of fresh troops allowed Grant to conduct his own attack the next day on April 7. After heavy fighting, the Confederate army withdrew from the field, providing Federal forces a tactical and bloody victory. Combined casualties exceeded 23,000 men.
General Grant honored the sacrifice of the soldiers who lost their lives at Shiloh in a congratulatory order that was issued on April 8th:
Whilst congratulating the brave and gallant soldiers, it becomes the duty of the general commanding to make special notice of the brave wounded and those killed upon the field. Whilst they leave friends and relatives to mourn their loss, they have won a nation's gratitude and undying laurels, not to be forgotten by future generations, who will enjoy the blessings of the best government the sun ever shone upon, preserved by their valor.
Highest Praise
The troops which did not arrive in time for the battle, are entitled to the highest praise for the untiring energy with which they pressed forward night and day to share the dangers of their comrades. One of those divisions (General George H. Thomas') had already under his command made its name honorable by one of the most memorable victories of the war-Mill Springs-on which the tide of success seemed to turn steadily in favor of the Union.
- Major General Don Carlos Buell, commanding Army of the Ohio
The troops that comprised Buell's command was transferred to the Department of the Cumberland [Army of the Cumberland] in late October 1862 after the Battle of Perryville. Prior to the reorganization, the War Department authorized a new Department of the Ohio on August 19, 1862, consisting of the states of Illinois, Indiana, Michigan, Ohio, and a large swath of Kentucky east of the Tennessee River.
There were several units that served at the Battle of Shiloh that were later attached to the new Army of the Ohio, including the 13th Kentucky Infantry [May 1863] and the 24th Kentucky Infantry [May 1863]. The 24th Kentucky was sent to garrison the newly established Camp Nelson in June 1863, named in honor of the officer who led the first contingent of the Army of the Ohio onto the field at Shiloh:
General William "Bull" Nelson.
The Action Commenced With Vigor
At 5:00 pm the head of my column marched up the bank at Pittsburg Landing and took up its position in the road under the fire of the rebel artillery, so close had they approached the Landing.
- Brigadier General William "Bull" Nelson, 4th Division, Army of the Ohio
The Army of the Ohio experienced their baptism by fire at Shiloh in April 1862. One division, under Brigadier General George H. Thomas, fought Confederate forces at the Battle of Mill Springs on January 19, 1862, but the rest of the army was not engaged. The army's first major test came not long after the massive Federal invasion of Tennessee.
With the captures Forts Henry and Donelson in February 1862, the US Army prepared for a major push to end the war in the Western Theater. According to General Ulysses S. Grant, who rose to national prominence after the major victories, “At the beginning of 1862, National troops occupied no territory south of the Ohio [River], except three small garrisons along its bank and a force thrown out from Louisville to confront that at Bowling Green.” The situation reversed in just three months as Grant's operations seized control of the Tennessee and Cumberland rivers, removing the major Confederate presence along the Tennessee-Kentucky border.
The Way Was Open
The Army of the Ohio advanced south from their base at Louisville, Kentucky toward Bowling Green before entering Tennessee. The army's forward movement into the Volunteer State forced the Confederate Army of Central Kentucky to abruptly withdraw from its defensive positions along the border and abandon Nashville. Advance elements of the US Army arrived at the outskirts of the city on February 23, 1862; Buell accepted the official surrender from civic leaders two days later. It was the first Confederate state capital to fall, and remained under Federal control for the remainder of the war.
Nashville became a forward operating base for Buell's army, which launched forays deep into enemy territory. He took the bulk of his army to support Grant's operations along the Tennessee River, resulting in the Battle of Shiloh on April 6-7, and later the Siege of Corinth in April-May. Other components of the army moved south to extend Federal occupation into Middle Tennessee and Northern Alabama.