Kammala wannan jumla: A farkon yakin, ya yi aiki a matsayi daban-daban, kafin ya zama colonel da kuma shugaban ma'aikatan sojojin Virginia karkashin Janar John Pope, inda ya ga aikin a yakin Cedar Mountain, na biyu na Bull Run, da kuma
Yaƙin Chantilly. Daga baya ya yi aiki a matsayin mataimakin shugaban ma'aikata na Sojojin Potomac, yana shiga cikin yaƙe-yaƙe na Kudancin Mountain da Antietam. A watan Disambar 1862, an sanya shi aikin ma'aikata a Washington, DC. A watan Fabrairun 1865, an nada shi babban jami'in Janar na Potomac a karkashin Janar George Meade, kuma ya shiga cikin yakin Hatcher's Run.