13 October 1963, the beginning of BEATLEMANIA

A new disease is sweeping through britain and doctors are powerless to stop it…it’s Beatlemania! (Sandy Gardiner)
London Palladium, here is where it all began, when the band appeared on the popular BBC television show “Val Parnell’s Sunday Night”.
On that magical Sunday evening, the Beatles performed in front of a national television audience of 15 million viewers. The band played a four-song set that included “From Me to You,” “I’ll Get You”, “She Loves You” and concluded its show with “Twist and Shout".

"Beatlemania", is a term that originated during the 1960s, to describe the intense fan frenzy directed toward British rock band "The Beatles", during the early years of their success. (source wikipedia).
There are multiple competing theories about the origin of the term.
Beatles' publicist Tony Barrow credited "The Press" for the term, but saw the phenomenon as beginning with the band's appearance on the London Palladium TV show on 13 October 1963, at which point he no longer had to contact the press, but had the press contacting him instead.
The scene at the Palladium was pure pandemonium. By the end of the show, more than 2,000 frenzied fans had collected outside on Oxford Street. “Screaming girls launched themselves against the police” the "Daily Herald" reported the next morning. (Bob Spitz)