Before their European tour in early 1970, the band recorded "Future Blues", an album containing five original compositions and three covers. "Let's Work Together", a Wilbert Harrison song, was the single chosen for release in Europe to coincide with the tour. At the band's insistence the U.S. release was delayed in order to offer the author's version a chance in the market first. Canned Heat had a big hit with "Let's Work Together" and was the band's only top ten hit to feature the vocals of Bob "The Bear" Hite. The album featured piano by Dr. John and an atypical jump blues style also. Some controversy was sparked by the moon landing/Iwo Jima album cover and the upside down American flag. The upside-down flag was Wilson's idea and was a response to his love of nature, growing environmentalism and concern that humankind would soon be polluting the moon as well as the Earth (as reflected in his song "Poor Moon").