While he was still an infant William Henry Powell's family moved to Cincinnati, Ohio. During his youth he began drawing and eventually received some rudimentary instruction from the artist James H. Beard (q.v.). In 1837 he returned to New York City and pursued his studied under the guidance of Henry Inman (q.v.). Powell proved himself a precocious student and within a year was exhibiting his paintings at the National Academy. Although he began his career working as a portraitists, he eventually turned his talents to historical painting.
In 1847 Powell was chosen to paint the last panel of the rotunda of the United States Capitol. [note--Powell a Western, chooses a Western subject, as had Inman] Although the commission had been originally awarded to Henry Inman, his Emmigration of Daniel Boon to Kentucky had probably not even been commenced when he died in 1846. Powell, as his successor, chose a new theme, The Discovery of the Mississippi by De Soto, for the panel. After deciding to complete the painting aborad, Powell embarked for Paris in 1848. He continued to reside in Paris and work in the paiting for the following five years [ptg.dated 1847-53] and during this period became acquainted with such artists as Thomas Couture and Horace Vernet. Upon returning to the United States Powell worked primarily in New York and Washington and received numerous commissions for portraits. Eventually, however, he was commissioned to paint Perry's Victory on Lake Erie for the state capitol of Ohio. Shortly after it was completed in 1863 he was commissioned to execute a larger version for the Senate wing of the United States Capitol. During the last decade of his life, Powell continued to work as a historical and portrait painter, but failed to receive any major commissions. His paintings were frequently included in the Academy's annual exhibitions up to the year before his death.