Samuel P. Heintzelman was a prominent Union general in the American Civil War, serving as commander of the 3rd Corps of the Army of the Potomac during the Peninsula and the Northern Virginia Campaigns of 1862.
Samuel Peter Heintzelman was born on September 30, 1805, in Manheim, Pennsylvania. He was the son of Peter and Ann Elizabeth Grubb Heintzelman. Heintzelman's father was a merchant, who also served as the village postmaster.
Heintzelman entered the United States Military Academy in 1822, graduating in 1826, seventeenth in his class of forty-one cadets. Among his classmates was future Confederate General Albert Sidney Johnston. After leaving West Point, officials commissioned Heintzelman as a brevet second lieutenant in the 2nd U.S. Infantry on July 1, 1826. For several years, he served on garrison duty near the Canadian border at Fort Gratiot, Fort Mackinac, and Fort Brady. On March 4, 1833, authorities promoted Heintzelman to first lieutenant. He then served on quartermaster duty in Florida during the Second Seminole War (December 23, 1835-August 14, 1842). On July 7, 1838, he received a promotion to captain.
Heintzelman married Margaret Stewart of Albany, New York, on December 5, 1844, at Buffalo, New York. The marriage produced two children, a daughter named Mary and a son named Stewart, who also became an officer in the U.S. Army.
During the Mexican-American War (April 25, 1846-February 2, 1848), Heintzelman served with General Winfield Scott's army. On October 9, 1847, officials brevetted him to the rank of major for "gallant and meritorious service" in the Battle of Huamantla.
At the conclusion of the Mexican-American War, Heintzelman transferred to California and then to the Arizona Territory. In December 1851, Heintzelman led a campaign against the Yuma Indians. During the course of the campaign, he established Fort Yuma near the confluence of the Colorado and the Gila Rivers. Officials brevetted Heintzelman to the rank of lieutenant colonel for his leadership during the campaign. On March 3, 1855, Heintzelman received a promotion to major of the 1st U.S. Infantry while campaigning against Indians along the Rio Grande. During his time in the Southwest, Heintzelman also found employment as president of the Sonora Exploring and Mining Company, serving as director of its field operations for a brief period while on leave from the army. In 1859, Heintzelman transferred to Texas. While serving there, he led a campaign, known as the First Cortina War, against Mexican outlaw and folk hero Juan N. Cortina.
When the American Civil War began, Heintzelman was serving in New York. Officials promoted him to the rank of colonel on May 14, 1861 and placed him in command of the newly formed 17th U.S. Infantry. Three days later authorities elevated Heintzelman to the rank of brigadier-general in the volunteer army and gave him command of the 3rd Division of the Army of Northeastern Virginia, serving under Brigadier-General Irvin McDowell. Heintzelman participated in the Union debacle at the Battle of Bull Run I on July 21, 1861. During the fighting, gunshot shattered his elbow.
Following the Union disaster at the Battle of Bull Run I (July 21, 1861), the US President Abraham Lincoln called upon Major General George B. McClellan to lead the Union war effort. McClellan soon set about reorganizing the Union armies in the field, but Lincoln had his own designs. On March 8, 1862, the President issued War Order No. 2, consolidating the Army of the Potomac's divisions into five corps. Lincoln went on to name Major General Irvin McDowell, Brigadier General Edwin V. Sumner, Heintzelman, Brigadier General E. D. Keyes, and Major General Nathaniel P. Banks to command the five corps respectively. Dutifully, on March 13, 1862 a disgruntled McClellan issued General Order No. 101 (Army of the Potomac), confirming the President's selections, including Sumner as the 2nd Corps commander. On May 5, 1862, Heintzelman received a promotion to major general of volunteers.
During the Peninsula Campaign Heintzelman participated prominently in the Battle of Yorktown (April 5, 1862-May 4, 1862), the Battle of Williamsburg (May 5, 1862), the Battle of Seven Pines (May 31, 1862-June 1, 1862), the Battle of Savage's Station (June 29, 1862), the Battle of Glendale (June 30, 1862), and the Battle of Malvern Hill (July 1, 1862). Authorities brevetted Heintzelman to the rank of brigadier-general in the regular army for "gallant and meritorious conduct "at the Battle of Seven Pines.
When McClellan's Peninsula Campaign began to disintegrate, Confederate General Robert E. Lee initiated an offensive against Major General John Pope's newly-formed Army of Virginia in the vicinity of Manassas, Virginia. To counter Lee's Northern Virginia Campaign, federal officials began shifting troops from McClellan's army to Pope's command. Heintzelman's corps joined Pope's army in time to participate in the Union disaster at the Battle of Bull Run II (August 28, 1862-August 30, 1862).
The performance of Heintzelman’s two more celebrated divisional commanders, Joseph Hooker and Philip Kearny, often overshadowed Heintzelman's own stature as a corps commander. Nonetheless, Civil War historians generally agree that Heintzelman's lackluster performance during the Peninsula and Northern Virginia Campaigns demonstrated his shortcomings leading large numbers of soldiers. Their conclusions are supported by the War Department's decision to remove Heintzelman from combat command a few months after the Battle of Bull Run II. On February 2, 1863, officials reassigned Heintzelman to command the XXII Corps, responsible for the defense of Washington, D.C. Heintzelman served in that position until October 13, 1863, when authorities reassigned him to command the Northern Department, headquartered in Columbus, Ohio, where he remained until October 1864. Afterwards, Heintzelman served on court-martial duty for the remainder of the war.
Heintzelman retired from volunteer service on August 24, 1865, but he remained in the regular army, commanding the 17th U.S. Infantry, mostly in Texas. He retired from the army on February 22, 1869. A special act of Congress, enacted on April 29 of that year, elevated Heintzelman to the rank of major general for "wounds received in the line of duty."
Heintzelman spent his remaining years living in Washington, D.C., where he died on May 1, 1880, at the age of seventy-five years. He is buried in Forest Lawn Cemetery, Buffalo, New York.
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"Samuel Peter Heintzelman," Ohio Civil War Central, 2021, Ohio Civil War Central. 17 Sep 2021 <http://www.ohiocivilwarcentral.com/entry.php?rec=960>
"Samuel Peter Heintzelman." (2021) In Ohio Civil War Central, Retrieved September 17, 2021, from Ohio Civil War Central: http://www.ohiocivilwarcentral.com/entry.php?rec=960
- Albert Sidney Johnston
- Army of Northeastern Virginia
- Army of the Potomac (USA)
- Army of Virginia
- Battle of Bull Run I
- Battle of Bull Run II
- Battle of Glendale
- Battle of Malvern Hill
- Battle of Savage's Station
- Battle of Seven Pines
- Battle of Williamsburg
- Edwin V. Sumner
- Erasmus D. Keyes
- General Orders, No. 134 (U.S. War Department)
- General Orders, No. 17 (U.S. War Department)
- General Orders, No. 217 (U.S. War Department) (1864)
- General Orders, No. 263 (U.S. War Department)
- General Orders, No. 316 (U.S. War Department)
- General Orders, No. 93 (U.S. War Department)
- George B. McClellan
- Irvin McDowell
- John Pope
- Mexican-American War
- Northern Virginia Campaign
- Peninsula Campaign
- Philip Kearny
- Robert E. Lee
- William B. Franklin
- William W. Loring
- Winfield Scott
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