May 26, 1967 - EMI releases "Sgt. Pepper's Lonely Hearts Club Band" a few days early in the UK. HISTORY.com It would go to number one for 15 weeks in the US and 22 weeks in the UK.
Perhaps The Beatles album with the most enduring legacy is Sgt Pepper's Lonely Hearts Club Band, released on May 26, 1967 at the height of the counterculture of the 1960s. The album capped off years of invention and innovation by the Fab Four, with their preceding albums Revolver and Rubber Soul marking a new era in their discography.
By August 1966 the Beatles had stopped touring, fresh from John Lennon's controversial statement that they were "more popular than Jesus", tired of their unceasing schedule and of Beatlemania. In the recording studio beginning November that year, they began producing songs initially inspired by Paul McCartney's idea involving an Edwardian military band. Two childhood-inspired songs "Strawberry Fields Forever" and "Penny Lane" were the results, but they were released as singles and left off the album.
The final product - released four days early in the UK and released on June 1, 1967 in the USA - contained innovative songs such as "Lucy in the Sky with Diamonds" (often erroneously thought to be a reference to LSD), "She's Leaving Home" and "A Day in the Life". It was an instant success, heralded by many as a groundbreaking album that bridged the gap between art and music, kickstarted the album era, foresaw progressive rock and partially gave the counterculture and the so-called 'Summer of Love' its immediate musical backdrop.
Over the years the album slipped in the favorability rankings among Beatles fans and critics, and was considered by some to be superfluous and inauthentic. Nevertheless the record had a substantial cultural and musical impact, selling 32 million copies to become the best-selling album of 1967 and one of the best-selling records of all time.