Complex sentence: He served as a captain in the War of 1812, and later as brigadier general of the Ninth Brigade of the Maryland Militia from 1818 to 1847.
Split into simpler sentences: He served as an officer of the Maryland State Militia and served as a Captain in the War of 1812. He was a Brigadier General of the 9th Brigade of the Maryland Militia from 1818 to 1847.