Simplify the following text for a Grade 6 native English-speaking person.
Original: JÃ zef Klemens PiÅ sudski ( , 5 December 1867 â `` 12 May 1935 ) was a Polish statesmanâ '' Chief of State ( 1918 â `` 22 ) , `` First Marshal '' ( from 1920 ) , and authoritarian leader ( 1926 â `` 35 ) of the Second Polish Republic .
Simplified: JÃ zef Klemens PiÅ sudski ( December 5 , 1867 â `` May 12 , 1935 ) was an important leader of Poland .