Whakaotihia te rerenga e whai ake nei: I whānau a Ewell ki Georgetown, District of Columbia. I whakatipuhia ia i Prince William County, Virginia, mai i te 3 o ona tau, i tetahi whenua tata ki Manassas e mohiotia ana ko "Stony Lonesome". Ko ia te tuatoru o nga tama a Dr. Thomas raua ko Elizabeth Stoddert Ewell; te mokopuna o Benjamin Stoddert, te Hekeretari tuatahi o te US Navy; te mokopuna o te Revolutionary War Colonel Jesse Ewell; me te tuakana o Benjamin Stoddert Ewell. I puta ia i te United States Military Academy i te 1840, tekau ma toru i tana akomanga o nga kaiako 42. E mōhiotia ana ia e ōna hoa ko "Old Bald Head" ko "Baldy". I whakawhiwhia ia hei tuarua tuarua i roto i te 1st U.S. Dragoons a i whakatairangahia ia ki te rangatira tuatahi i te 1845. Mai i te 1843 ki te 1845 i mahi tahi ia me Philip St. George Cooke me Stephen Watts Kearny i runga i te kawenga kaitiaki i te Santa Fe me Oregon Trails. I te Pakanga o Mexico-Amerika, e mahi ana i raro i a Winfield Scott, i mohiotia ia ka whakatairangahia hei rangatira mo tana maia i Contreras me
Ko Churubusco. I Contreras, i whakahaerehia e ia he tirotirohanga i te po me te kaihoahoa a Kapene Robert E. Lee, tana rangatira o muri mai.