Simplify the following text for a Grade 11 native English-speaking person.
Original: Pope Paul VI , born Giovanni Battista Enrico Antonio Maria Montini ( 26 September 1897 â `` 6 August 1978 ) , reigned as Pope of the Catholic Church and Sovereign of Vatican City from June 21 , 1963 , until his death on August 6 , 1978 .
Simplified: Pope Paul VI , born Giovanni Battista Enrico Antonio Maria Montini , was the Pope of the Roman Catholic Church from 1963 until his death in 1978 .