Simplify the following text for a Grade 8 native English-speaking person.
Original: John Collings Willcock ( 9 August 1879 â `` 7 June 1956 ) was the 15th Premier of Western Australia from 20 August 1936 to 31 July 1945 .
Simplified: John Collings Willcock ( 9 August 1879 â `` 7 June 1956 ) was the 15th Premier of Western Australia .