composing their own material, combining US forms of music and infusing it with a high energy beat. Beat bands tended towards "bouncy, irresistible melodies", while early British blues acts tended towards less sexually innocent, more aggressive songs, often adopting an anti-establishment stance. There was, however, particularly in the early stages, considerable musical crossover between the two tendencies. By 1963, led by the Beatles, beat groups had begun to achieve national success in Britain, soon to be followed into the charts by the more rhythm and blues focused acts. "I Want to Hold Your Hand" was the Beatles' first number one hit on the Billboard Hot 100, spending seven weeks at the top and a total of 15 weeks on the chart. Their first appearance on The Ed Sullivan Show on 9 February 1964, drawing an estimated 73 million viewers (at the time a record for an American television program) is considered a milestone in American pop culture. During the week of 4 April 1964, the Beatles held 12 positions on the Billboard Hot 100 singles chart, including the entire top five. The Beatles went on to become the biggest selling rock band of all time and they were followed into the US charts by numerous British bands. During the next two years British acts dominated their own and the US charts with Peter and Gordon, the Animals, Manfred Mann, Petula Clark, Freddie and the Dreamers, Wayne Fontana and the Mindbenders, Herman's Hermits, the Rolling Stones, the Troggs, and Donovan all having one or more number one singles. Other major acts that were part of the invasion included the Kinks and the Dave Clark Five. The British Invasion helped internationalize the production of rock and roll, opening the door for subsequent British (and Irish) performers to achieve international success. In America it arguably spelled the end of instrumental surf music, vocal girl groups and (for a time) the teen idols, that had dominated the American charts in the late 1950s and 1960s. It dented the careers of established R&B acts like Fats Domino and Chubby Checker and even temporarily derailed the chart success of surviving rock and roll acts, including Elvis. The British Invasion also played a major part in the rise of a distinct genre of rock music, and cemented the primacy of the rock group, based on guitars and drums and producing their own material as singer-songwriters. Following the