Included in a temporary exhibit about the Underground Railroad at the Visitor Center of the Herbert Hoover National Historic Site in West Branch, Cedar County, Iowa, was a profile of the Coppock family. President Hoover was descended from a Coppock through his father's family according to this source.
Edwin and Barclay Coppock were deemed "Heroes of Harper's Ferry" by Eugene V. Debs (!) in this 1914 article. As Debs stated, the brothers were born near Salem, Ohio, a town known for its abolitionist sentiment, of Quaker parents. Their widowed mother, Ann, later moved to Springdale, Cedar Co., Iowa, a community also settled by Quakers.
John Brown, the Abolitionist, spent the winter of 1857 in Springdale, Iowa. In 1858 Brown led a group through the "Underground Railroad;" the former slaves went through Detroit and into Canada. The Coppoc brothers of Springdale signed on to John Brown's "Provisional Army." Photographs of members of the "Provisional Army," including the Coppocs, can be seen here. [References to the Coppoc brothers in John Brown bio here].
A voice from Harper's Ferry...by Osborne Perry Anderson, published in 1861, included Eleven Orders From John Brown, including Order #1 which stated that "Captain Owen Brown, F. J. Merriam, and Barclay Coppic to remain at the old house (Kennedy Farm) as sentinels" and Order #9 which stated that Lieutenant Albert Hazlett and Private Edwin Coppic were to hold the Armory opposite the engine house after it had been taken... ."
More detail concerning John Brown's raid on Harper's Ferry can be found here (some of the names are wrong).
Edwin Coppock was captured, imprisoned, and hung. He was buried at Hope Cemetery, Columbiana County, Ohio.
Col. Robert E. Lee's Report of 19 October 1859, concerning the attack at Harper's Ferry can be seen here.