Complex sentence: Shortly after writing "The Road to the South", Duẩn was appointed to the Secretariat in 1956, and in 1957, he was given a seat in the Politburo.
Split into simpler sentences: Shortly after writing "The Road to the South", Duẩn was appointed to the Secretariat in 1956. In 1957, he was given a seat in the Politburo.