William Sonntag was born in East Liberty, Pennsylvania in March 1822. Against the objections of his parents Sonntag pursued a career in art. In the 1840s, Sonntag was believed to have studied with Godfrey Frankenstein at the Cincinnati Academy of Fine Arts. While in Cincinnati he kept a studio and made many trips to the Ohio River Valley and the hills of Kentucky to paint sweeping picturesque landscapes. His style was heavily influenced by the esteemed landscape painter, Thomas Cole.

Prior to traveling to Florence in 1855, Sonntag collaborated with John C. Wolfe on a large painting of Milton’s Paradise Lost and Paradise Regained. Upon his return from Europe he settled in New York City. By the 1860s Sonntag was well known for his romantic dramatic landscape renderings of New England, upstate New York and Italy. He painted the Alleghenies, Mt. Adams, the Shenandoah Valley, Adirondacks and the White Mountains.

Sonntag was an Associate and Academician at the National Academy of Design and a member of the American Water Color Society, the Artists Fund Society and the American Art Union. His work is represented in the permanent collections of the Metropolitan Museum of Art; Corcoran Gallery of Art; Peabody Institute; Berkshire Museum; Brooklyn Museum; the Fogg Museum; Harvard University; Vassar College Art Gallery; Cincinnati Art Museum and more.

He died in New York City in 1900; known as one of the most accomplished American landscape painters.