Whakaotihia te rerenga e whai ake nei: I te timatanga o te Pakanga a-Rohe, i whakahau a Mansfield i te Tari o Washington (Paenga-whāwhā 27 - Akuhata 17, 1861), a i whakatairangahia ia ki te rangatira rangatira i te Mei 6, 1861. I taunaki a Winfield Scott ki a Mansfield mo te rangatira o te ope o nga kaitohutohu i whakaarahia i Washington DC i taua puna, engari ko te whakahau i haere ki a Irvin McDowell. Kaore a Mansfield i whakaarohia ko te whiringa pai na te mea he koroheke ia, he ruarua hoki o nga hoia tuku noa, me te akiaki a te tari mo te tere tere ki Richmond e mutu ai te pakanga i roto i etahi marama, ana kaore hoki ia i whai kaitautoko torangapu i Washington. Whai muri i te hinganga o te Uniana i Bull Run, i whakawhiwhia a George McClellan ki te rangatira o te pakanga i te Whare Taonga o te Rawhiti, a, ko nga tumanako a Mansfield mo te whakahau ope taua i pakaru ano. Kaore hoki a McClellan i tuku ki a ia he whakahau i roto i te ope hou o te Potomac. I tū a Mansfield ki
Hatteras Inlet, North Carolina, i te Oketopa, whai muri i te pakanga i whawhai ai a Benjamin Butler i Akuhata. I noho ia hei rangatira pirihimana i te Tari o Virginia mai i te Poutu-te-rangi ki te Pipiri 1862. Ko tana mahi whawhai anake i tenei wa ko te pupuhi o nga papahiko takutai mai i Hampton Roads ki te "CSS Virginia" i tana pakanga moana ki te "USS Monitor" i te Poutu-te-rangi 9, 1862. Tae noa ki te ngahuru o te tau 1862, i whakahau a Mansfield i te Wahanga o Suffolk o te VII Corps o te Tari o Virginia i te taha o Suffolk.