Kammala wannan jumla: A watan Yunin 1861, an ba O'Neal mukamin kyaftin kuma ya umurci kamfanonin sojoji uku. Bayan ya isa Richmond an nada shi babban jami'in 9th Regiment Alabama Infantry kuma an ci gaba da zama Laftanar Kanar a cikin fall. A watan Maris na shekara ta 1862, an nada shi a matsayin colonel na 26th Alabama infantry, kuma ya umurci wannan rundunar a lokacin yakin basasa na Peninsula. A yakin Bakwai Bakwai, an kashe dokinsa a ƙarƙashinsa, kuma ya ji rauni sosai ta hanyar fashewa. Ya karbi yabo mai yawa don aikinsa a yakin Chancellorsville. A shekara ta 1863, ya umurci brigade a Maj. Janar Robert E. Rodes, kuma ya jagoranci shi a yakin Gettysburg, yakin Manassas Gap da kuma a
Yaƙin Mine Run. A farkon shekara ta 1864, an aika da rundunarsa zuwa Alabama don daukar nauyin da aka rage, amma an umurce shi da sauri zuwa Dalton, Georgia, inda O'Neal ya jagoranci brigade Brig. Janar James Cantey a cikin sojojin Tennessee. O'Neal ya umurci wannan brigade a lokacin da ya rage na Atlanta Campaign. Bayan da aka ba Lieutenant General John Bell Hood umurnin Sojojin Tennessee, an sauƙaƙe O'Neal kuma ya yi aiki a kan aikin da ya rage don sauran yakin. An nada shi brigadier janar a ranar 6 ga Yuni, 1863, amma Janar Robert E. Lee ya yi wannan alƙawari kuma shugaban Confederate Jefferson Davis ya soke haɓakawa.