The "British Invasion" was one of the most important musical events in history, and there's no disputing that the Beatles launched it. The musical and cultural impact of the British Invasion cannot be overstated:
""I Want to Hold Your Hand" zoomed to the top of the USA charts just as The Beatles came to America for the first time. Their historic appearance on The Ed Sullivan Show on February 9, 1964 was watched by what was then the largest television audience in history. This appearance was a remarkable social and cultural milestone of the 1960's, and marked the dramatic start of the British Invasion.
The Beatles' two year backlog of hit songs from England quickly came to dominate the American charts, and on April 4 of that year they occupied the top five spots on the Billboard magazine Hot 100 music survey, a feat unmatched before or since. Their success opened the floodgates for other British acts to market their music in the United States, beginning with The Dave Clark Five. They were quickly followed (in rough chronological order of US chart success) by Gerry and the Pacemakers, Peter and Gordon, The Animals, The Kinks, Manfred Mann, Herman's Hermits, the Rolling Stones,The Yardbirds, The Zombies, and Petula Clark by the end of 1964."
http://en.wikipedia.org/wiki/British_Invasion