Ormsby MacKnight Mitchel

July 28, 1809–October 30, 1862

Ormsby MacKnight Mitchel was a world-renowned astronomer and a Union major general during the American Civil War.

Portrait of Ormsby MacKnight Mitchel

Ormsby M. Mitchel helped plan and authorize James J. Andrews’ unsuccessful raid on the Western and Atlantic Railroad, in Northern Georgia, also known as the Great Locomotive Chase. [Wikimedia Commons]

Early Life

Ormsby MacKnight Mitchel was born near Morganfield, in Union County, Kentucky on July 28, 1809. He was the youngest child of Virginia planter John Mitchel and Elizabeth McAllister, who had moved their family and slaves to Kentucky in 1804.

The family patriarch died unexpectedly when Ormsby was three years old, and his mother moved the younger children to live with her daughter in Lebanon, Ohio in 1814. Mitchel attended local schools there and his mother also educated him at home.

His family’s financial needs forced young Mitchel to seek employment at age twelve or thirteen. Nonetheless, he maintained his thirst for education. In 1825, Mitchel successfully petitioned Judge John McLean and U.S. Representative Thomas Ross for an appointment to the United States Military Academy.

U.S. Military Academy Cadet

Mitchel entered West Point on July 1, 1825. His classmates included future Confederate Generals Robert E. Lee and Joseph E. Johnston. Mitchel excelled at the Academy, graduating fifteenth in his class of forty-six cadets on July 1, 1829.

U.S. Army Officer

After graduation, the army brevetted Mitchel to second lieutenant and assigned him to the U.S. 2nd Artillery. However, his mathematical abilities were so noteworthy that officials quickly detached him to serve as an assistant professor of mathematics at West Point.


While teaching at West Point, Mitchel met Louisa (Clark) Trask, a nineteen-year-old widow with one child. Over the initial objections of her family, the young widow and Mitchel became engaged. On August 28, 1831, the army ordered Mitchel to join his regiment for garrison duty at Fort Marion, Florida. Prior to departing, the couple married on September 10, 1831. Their union produced seven children, five of whom survived infancy.

Army Resignation

Mitchel and his bride lived in Florida for only one year. On September 30, 1832, Mitchel resigned his commission, and the couple moved to Ohio.

Lawyer, Professor, and Engineer

An exceptionally brilliant man, Mitchel settled in Cincinnati, where he passed the Ohio bar exam and opened a law practice in 1832. Mitchel continued to practice law until 1834, but his real interests were mathematics and the sciences. In 1834, he secured a position as a Professor of Mathematics, Philosophy, and Astronomy at Cincinnati College (now the University of Cincinnati). Mitchel held that position until 1844. During his tenure, Mitchel’s mathematical prowess enabled him to secure the position of chief engineer for the construction of the Little Miami Railroad from 1836 to 1837.


While at Cincinnati College, Mitchel pursued his true passion–-astronomy. He became a nationally renowned lecturer on the topic, organized the Cincinnati Astronomical Society, and was instrumental in the construction of the Mitchel Observatory, a world-class facility on Mt. Adams in Cincinnati. Mitchel was the director of the observatory for fourteen years after its opening in 1845.

During his tenure, Mitchel also served a one-year term as Adjutant-General of the State of Ohio (1847‑48). He also served two terms as Chief Engineer of the Ohio and Mississippi Railroad, (1848‑49 and 1852‑53). In 1859, Mitchel accepted a position as an astronomer at the Dudley Observatory in Albany, New York.

Civil War

Union Army Officer

When the American Civil War erupted, Mitchel accepted a commission as a brigadier general of Ohio volunteers on August 8, 1861. Five weeks later, on September 19, 1861, the War Department issued General Orders, No. 80, placing Mitchel in command of the Department of the Ohio. Mitchel immediately set about organizing defenses around Cincinnati and in northern Kentucky, but he served as department commander for only two months, because the U.S. Senate did not confirm his promotion to major general. On November 9, 1861, the War Department issued General Orders, No. 97, which reorganized the Department of the Ohio and placed Major General Don Carlos Buell in command. Buell arrived in Cincinnati and replaced Mitchel on November 15.

Army of the Ohio Divisional Commander

After Buell assumed command of the Department of the Ohio, army officials assigned Mitchel to command the 3rd Division of the Army of the Ohio and ordered him to Louisville, Kentucky for recruiting duties. During the spring of 1862, he took part in the Army of the Ohio’s occupation of Bowling Green, Kentucky (February 9, 1862) and of Nashville, Tennessee (February 23, 1862).

Activities in Tennessee and Alabama

On March 18, 1862, Mitchel moved his division from Nashville and occupied Murfreesboro, Tennessee, approximately thirty-five miles to the south. By early April, he had moved another twenty-five miles south to Shelbyville, Tennessee, where the local citizens warmly received his troops.

Shortly after, Buell led most of the Army of the Ohio toward Pittsburg Landing, Tennessee to reinforce Brigadier General Ulysses S. Grant‘s Army of the Tennessee at the Battle of Shiloh (April 6-7, 1862), Mitchel moved his division another sixty miles into Dixie and seized Huntsville, Alabama on April 11. Mitchel’s incursion into Alabama marked the deepest penetration into the South by federal troops during the Civil War to date. It also severed the Mississippi & Charleston Railroad, the only rail line linking the Mississippi River to the eastern half of the Confederacy.

Andrew’s Raiders

While Mitchel was moving south from Nashville to Huntsville, he aimed to capture Chattanooga in eastern Tennessee. To achieve that end, he hatched a plan to send twenty-four saboteurs, led by a civilian named James J. Andrews, into northern Georgia to cut the Western and Atlantic Railroad, which connected Chattanooga with Atlanta.

Known as Andrew’s Raiders, twenty of the Yankees (eighteen Ohio soldiers and two civilians) captured a Confederate locomotive named the General on April 12, 1862, south of Chattanooga. They headed north, cutting telegraph lines and attempting to destroy track as two other Confederate trains—the Yonah and the Texas—pursued them.

The Raiders eventually ran out of fuel and abandoned the General, scattering across northern Georgia. Rebel pursuers captured all of them within the next two weeks. The Confederates hanged six of the conspirators, including Andrews, as spies. Eight others escaped and made their way back to Union lines. The Confederate government held the remaining six as prisoners of war and exchanged them eleven months later. Although a failure, Hollywood later immortalized Andrews’ Raid on film as the Great Locomotive Chase.

Attempt to Resign

After seizing Huntsville, Mitchel failed to convince his superiors, (Buell and, later, Major General Henry W. Halleck) to provide him with enough troops to attempt to capture Chattanooga. Instead, Halleck focused on the rail hub at Corinth, Mississippi. After Corinth fell (May 30, 1862), Buell visited Mitchel in Huntsville to discuss future strategies. The two generals disagreed, and on June 30, Mitchel telegraphed Secretary of War Edwin Stanton, “Finding it impossible to serve my country longer under my present commander, I have to-day forwarded, through him, my unconditional resignation, and respectfully solicit leave of absence for twenty days.”

Major General

Stanton replied two days later, granting Mitchel’s request for leave, but rejecting his resignation. Upon receiving Stanton’s reply, Mitchel traveled to New York. While waiting nearly all summer for further orders, the War Department promoted Mitchel to the rank of major general in July, effective April 11, 1862.


In early September, Halleck (now General-in-Chief of Union armies) appointed Mitchel as commander of the 10th Army Corps and Department of the South, headquartered in South Carolina. Mitchel arrived in the Palmetto State on September 15 and assumed command on September 17, 1862. His tenure was brief, however. After contracting yellow fever, Mitchel died on October 30, 1862, at Beaufort, South Carolina, at age fifty-two. His body was sent to New York, where he was buried at Green-Wood Cemetery in Brooklyn.

Citation Information

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  • Article Title Ormsby MacKnight Mitchel
  • Date July 28, 1809–October 30, 1862
  • Author
  • Keywords Ormsby MacKnight Mitchel
  • Website Name American History Central
  • Access Date July 20, 2024
  • Publisher R.Squared Communications, LLC
  • Original Published Date
  • Date of Last Update January 12, 2024