Complex sentence: He was member of the First Council of the Seventy from 1845 to 1854 and served in the First Presidency under church president Brigham Young from 1854 to 1856.
Split into simpler sentences: He was member of the First Council of the Seventy from 1845 to 1854. He also served in the First Presidency under church president Brigham Young from 1854 to 1856.