In 1969, after researching its concepts, the members of the ISB had joined the Church of Scientology, and expressed some of their changing views on their subsequent studio album, Changing Horses, later in the year. In November 1969, at the Hotel Chelsea in New York City, the ISB met two ex-members of David Medalla's kinetic art group the Exploding Galaxy, after the troupe unsuccessfully tried to negotiate a recording contract with MGM Records. Former members Malcolm Le Maistre and Rakis, as well as their newly formed dance ensemble the Stone Monkey, took residency at the ISB's commune in Glen Row to help the band, especially Robin Williamson, realise their vision for a multi-media stage act. Described as a "surreal parable in song and dance" by Williamson, U was "neither a pageant, a play, dance, theater, nor pantomime, though there were elements of all of those" in the show. For the plot, Williamson explained "the vague notion was, a soul incarnates out of nowhere, lives, and then vanishes again at the other end. Hence the idea 'U'", although the performances themselves hardly followed a coherent storyline. On 8 April 1970 the three-hour U show opened at London's Roundhouse where it ran for ten consecutive days. As many as 12 dancers accompanied the band on stage; the dancing aspect was reminiscent of the group's early performing days with the duo Mimi and Mouse. Another booking, this time for six days at the Fillmore West in San Francisco, came at the ISB's own expense, and the financial fallout forced the group to complete the shows without the Stone Monkey in a standard concert format. In an attempt to recoup the financial losses of the "U" show, record producerJoe Boyd booked the band, along with session musiciansJanet Shankman, Peter Grant, and Maistre, into a San Francisco studio to record the nearly two hours of material that is featured on the double album. U was recorded in just 48 hours; Williamson recalled "We just went day and night for two days and two nights, in shifts, and finished. I can't remember what the reasons were, but we had to be done in a hurry. In a way, it seemed to fit". Regardless of the time constraints, the album still contained characteristically complex instrumentals and overdubbing. The music on the album was taken from the songs the band performed on the U tour, showcasing a staggering diversity of psychedelia, folk rock, and traditional folk arrangements long associated with the group, as well as new, highly progressive elements.
Release
U was released in October 1970 on the Elektra label. In the US, the album peaked at number 183 on the Billboard 200, remaining on the charts for three weeks, and on the UK Albums Charts it managed to reach number 34 during a two-week stay. Also, in Melody Maker magazine the album charted in the top 20, before dropping off in a few weeks. The album's cover by Shankman was literal interpretation of the show as it featured a mult-colored "U". Inside the gatefold sleeve were photographs depicting the band and the Stone Monkeys in the midst of a performance of the "U" show.