What was The Beatles' first number one single?

The Beatles have the most number ones of any artist in musical history, but which track was their first chart-topper? And who wrote it?

50 years ago: The Beatles' first #1 hit

Songs with chord changes light up brain's reward centre

Eric Clapton v. George Harrison: The Duel from All Angles

Love Me Do - Wikipedia

Beatles, Members, Songs, Albums, & Facts

THE BEATLES songs and albums

The Lost Album of the Beatles review – deeply researched what-ifs

Every UK Number 1 single by The Beatles

ONES – The Beatles #1 Hits

THE BEATLES songs and albums