Complex sentence: In January 1964 it became the British group's first big hit, reaching number one on the UK Singles Chart then in April 1964 later reaching number 6 on the U.S. pop singles chart, becoming the first British Invasion hit by an artist other than The Beatles.
Split into simpler sentences: In January 1964, it became the British group's first big hit, reaching number one on the UK Singles Chart. In April 1964, it reached number 6 on the American U.S. pop singles chart, becoming the first British Invasion hit by an artist other than The Beatles.