Nyorai kupfuurira kweiyi ndima - Muna June 1861, O'Neal akagadzwa kuva kaputeni ndokutungamirira makambani matatu evarwi. Paakasvika kuRichmond akagadzwa kuva mukuru we9th Regiment Alabama Infantry uye akasimudzirwa kuva lieutenant colonel mumatsutso. Muna Kurume 1862, akagadzwa colonel we26th Alabama infantry, uye akatungamira chirongwa ichi panguva yePeninsula Campaign. Muhondo yeSeven Pines, bhiza rake rakaurayiwa pasi pake, uye akakuvadzwa zvakakomba nechidimbu chebhomba. Akarumbidzwa zvikuru nokuda kwebasa rake muHondo yeChancellorsville. Muna 1863, akatungamira brigade mu Maj. Gen. Robert E. Rodes's division, uye akaitungamira muHondo yeGettysburg, Hondo yeManassas Gap uye muHondo yeMine Run
. Pakutanga muna 1864, chikwata chake chakatumirwa kuAlabama kunotora mauto ayo akaderera asi akakurumidza kurairwa kuDalton, Georgia, uko O'Neal akatora mutungamiri weBrig. Gen. James Cantey's brigade muuto reTennessee. O'Neal akarayira boka iri munguva yasara yeAtlanta Campaign. Pashure pokunge Lt. Gen. John Bell Hood apiwa mutungamiri weHondo yeTennessee, O'Neal akazorodzwa uye akashanda pabasa rakasununguka kwehondo yakasara. Akagadzwa brigadier general musi waChikumi 6, 1863, asi kugadzwa uku kwakaitwa naGeneral Robert E. Lee uye kukwidziridzwa kwakabviswa neMutungamiri weConfederate Jefferson Davis.