Harry Jacobus was deeply involved in the San Francisco Abstract Expressionism movement of the early 1950s. After serving in World War II, he moved to California, enrolling first at the Oakland School of Arts and Crafts and later The California School of Fine Arts, where he studied with Clyfford Still and David Park. He also met fellow student Jess, and in turn Robert Duncan. Together, they opened the King Ubu Gallery in December 1952, which quickly—though briefly—became the center of the avant garde art, music, and poetry scene in San Francisco. The King Ubu Gallery hosted exhibitions by artists such as Elmer Bischoff, David Park, Hassel Smith, Jess, Lyn Brockway, Roy De Forest, and Deborah Remington, as well as poetry readings and performances. During the 50s and 60s, Jacobus traveled through Europe, particularly Hydra, Greece, as well as Mexico. Back in California, he lived at the "Ghost House" on Franklin Street and later in Stinson Beach, always remaining close to Duncan and Jess, physically as well as artistically. Jacobus was profoundly influenced by Duncan and Jess’s ideas about imagination, as well as by French Modern painters, particularly les Fauves. Artists and critics often focus on the romanticism, color, and light of Jacobus’s paintings. Duncan called him “a painter in a mixed light,” noting that his work "is an intimation of the beauty around us as it is within us."