Complex sentence: His 43-year-long career at the newspaper began in 1941 when he was hired as a reporter which led to him becoming city editor (1956-1966) and managing editor (1966-1979).
Split into simpler sentences: His 43-year career at the newspaper began in 1941 when he was hired as a reporter. He later served as city editor (1956-1966) and managing editor (1966-1979).