Complex sentence: Thereafter, he left Czechia for one year and after return he started work as a clerk in the post office, but soon, he was appointed a director of the library of the Ministry of Post and director of the Postal Museum and Archive.
Split into simpler sentences: Thereafter, he left Czechia for one year and after his return he started working as a clerk in the post office. Soon after, he was appointed director of the library of the Ministry of Post, and director of the Postal Museum and Archive.