William Louis Sonntag was born in East Liberty, Pennsylvania (now part of Pittsburgh), and was raised in Cincinnati, Ohio. His father discouraged his interest in art but after two failed apprenticeships, one to a carpenter and the other to an architect, acquiesced to the inevitable. Sonntag, who is thought to have studied at the Cincinnati Academy of Fine Arts, developed his skills as a landscape painter during the 1840s. His reputation grew thanks to the works that he exhibited at the newly founded Western Art-Union in Cincinnati and the American Art Union in New York. Sonntag began to exhibit at the Pennsylvania Academy of the Fine Arts in 1853, the year he made his first visit to Europe with fellow Ohio painters John Robinson Tait and Robert S. Duncanson. After returning from a second trip to Italy 1857, Sonntag settled in New York, where he was elected an associate member of the National Academy in 1860 and a full academician the following year. Sonntag died in New York City.