Complex sentence: John Appleton (1815--1864) was appointed Chargé d'Affaires to Bolivia in 1848, Assistant Secretary of State in 1857 serving to 1860 when appointed United States Ambassador to Russia serving to 1861.
Split into simpler sentences: John Appleton (1815--1864) was appointed Chargé d'Affaires to Bolivia in 1848. He later served as Assistant Secretary of State in 1857 serving to 1860 when appointed United States Ambassador to Russia serving to 1861.