Rubuta ci gaba ga wannan sakin layi - Gregg ya umurci rundunar sojan doki da suka kasance a kusa da Petersburg yayin da Sheridan ya shiga cikin Shenandoah Valley Campaign da Jubal Early. A matsayinsa na kwamandan sojan doki, Gregg ya duba ƙungiyoyin ƙungiyoyi daban-daban a cikin Siege na Petersburg. Ƙungiyar Gregg ta kasance musamman a yakin na biyu na Deep Bottom, yakin na biyu na Ream's Station
, da kuma yakin Peebles 'Farm. Kusa da ƙarshen aikinsa, an ci gaba da shi zuwa matsayi na babban janar.