 Kunyora kuenderera mberi kweiyi ndima - Apo South Carolina yakaparadzana neUnited States muna Zvita 1860, Gregg akabatsira kuronga 1st South Carolina Volunteers, uye akashanda semukuru wekutanga wechiremera. Akava brigadier general uye akashanda muA. P. Hills Light Division. Boka rake rakaita basa rakatanhamara pakurwiswa kwaHill pamitsetse yeUnion paHondo yeGaines Mill. Gregg akawana mukurumbira paHondo yechipiri yeBull Run apo varume vake vakadzinga kurwisa kweUnion nhanhatu, uye akashanda muRobert E. Lees Maryland Campaign. PaAntietam akakuvadzwa muchidya nebara rimwe chetero rakauraya Brig. Gen. Lawrence OBryan Branch. 