Opdycke was born on a farm in Hubbard, Ohio, to a military family. His father fought in the War of 1812 and his grandfather was a captain in New Jerseymilitia in the American Revolution. His older brother Henry served in the Kansas cavalry during the Civil War. Opdycke was educated in the Hubbard schools. He engaged in various business pursuits in Ohio and California.
During the Franklin-Nashville Campaign, Opdycke distinguished himself at the Battle of Franklin. As the Confederate troops under Lt. Gen.John Bell Hood approached, his division commander, Brig. Gen. George D. Wagner, ordered Opdycke and the other two brigade commanders to take up hasty defensive positions in front of the Union fortified line. Opdycke challenged this order, argued with Wagner, and marched his men into a reserve position behind the fortifications. When the Confederate assault broke the Union line near the Columbia Pike, Opdycke quickly redeployed his men into line of battle, straddling the road, and they were confronted by masses of fleeing Union soldiers, pursued by Confederates. Opdycke ordered his brigade forward to the works. At the same time, his corps commander, Maj. Gen. David S. Stanley, arrived on the scene. He later wrote, "I saw Opdycke near the center of his line urging his men forward. I gave the Colonel no orders as I saw him engaged in doing the very thing to save us, to get possession of our line again." The counterattack turned the tide and the Union Army achieved an important victory.[2]
Opdycke was honored for his service at Franklin with a brevet appointment to major general of volunteers. He was promoted to a full brigadier general on July 26, 1865.[3]
Postbellum life
Opdycke resigned from the army in 1866 and moved to New York City, where he engaged in the dry goods business. He wrote several articles on the war, and was active in veterans affairs. He died in New York at the age of 54 of an accidental gunshot to the abdomen, apparently while he was cleaning the weapon.[3]
Eicher, John H., and David J. Eicher. Civil War High Commands. Stanford, CA: Stanford University Press, 2001. ISBN0-8047-3641-3.
Jacobson, Eric A., and Richard A. Rupp. For Cause & for Country: A Study of the Affair at Spring Hill and the Battle of Franklin. O'More Publishing, 2007. ISBN0-9717444-4-0.
Warner, Ezra J. Generals in Blue: Lives of the Union Commanders. Baton Rouge: Louisiana State University Press, 1964. ISBN0-8071-0822-7.
Opdycke, Emerson. To Battle for God and the Right: The Civil War Letterbooks of Emerson Opdycke. Edited by Glenn V. Longacre and John E. Haas. Urbana: University of Illinois Press, 2003. ISBN978-0-252-02774-1.