Complex sentence: In 1817-18 he served under Jackson during the Seminole War and the invasion of Florida and in 1832-33 commanded the national forces in Charleston harbor at the time of the nullification movement in South Carolina.
Split into simpler sentences: In 1817--18 he served under Jackson during the Seminole War and the invasion of Florida. In 1832-33, Ripley commanded the Federal forces in Charleston harbor at the time of the nullification movement in South Carolina.