Complex sentence: He served as a Naval Commissioner from 1830 to 1832 and commanded the Philadelphia Navy Yard from 1838 to 1841, in 1846, and again from 1853 to 1861.
Split into simpler sentences: He served as a Naval Commissioner from 1830 to 1832. Stewart commanded the Philadelphia Navy Yard from 1838 to 1841, in 1846, and again from 1853 to 1861.