His father died when he was a boy, and he and his mother left Maryland for Cincinnati, as she had family there;[1] in that city he received some instruction from Theodore S. Parvin, who later became a prominent educator in Iowa.

He later described the incident:[2] At the height of the excitement, I drew a large caricature, representing the Capitol building on wheels, and oxen pulling one way, upon whose shoulders were placed heads of members who voted for removal.

Charles Anderson Dana provided him with a letter of introduction to Thomas Hicks, whose pupil he became, and in whose studio he met William Makepeace Thackeray.

[1] Yewell never returned to Iowa to live, though he visited regularly, and married a local woman, Mary Elizabeth (Mollie) Coast, in 1863.

[3] It is suspected that Yewell returned to the United States due to the behavior of his wife, who had shocked the American expatriate community in Rome; the couple were divorced the next year, and she married the English painter Edwin Ellis.

[3] Yewell maintained deep ties with his patrons from Iowa, and earned many portrait commissions from them; even so, upon his return to America settled in New York City, where the chances of finding work were better.

In 1881 he was reported to be designing a frieze for the Veterans Room in the Seventh Regiment Armory on Park Avenue, a task he undertook for Louis Comfort Tiffany.

Elected an Associate of the National Academy of Design in 1862, and made a full member in 1880, he contributed to exhibitions there beginning in 1852; apart from 1872 to 1876 his works were rarely absent from the yearly shows.

Among them are his notebooks, many of which he copied from his earlier journals, which he kept sporadically throughout his career and which provide valuable insight not only into his creative life but into the everyday affairs of the period.