According to the War of 1812 Federal Pensioners List, pp. 1246-1247, William and Chandler Maddox of Abbeville, SC, fought in the war. They were nephews of Benjamin III. It’s interesting to note that John C. Calhoun, a progenitor of the war, lived very close to the Maddoxes in Abbeville.
According to F. Edward Wright’s Maryland Militia: War of 1812, Volume 5: St. Mary’s and Charles Counties, Benjamin, Frederick, Naolty of M., Notley, Gilbert and William R. Maddox enlisted in the Maryland militia. These men’s relationships to our line have not yet been resolved, but they are likely cousins or nephews of our Benjamin II or Benjamin III. The British invaded Washington along the Potomac River, and Charles County was the scene of some fighting and looting.
hisXmark 
I have always been curious about this Frederick. There’s is a bible record (transcription, not the original bible, alas) that names a Frederick as Mark Maddox’s father. There are many clearly erroneous parts of this transcription, so it’s tempting to throw it out altogether. Yet, it supposedly came from a bible belonging to Mark’s daughter. And there is no other extant document of Mark’s father, so where would this notion come from? I have not researched this Frederick much, but I know he was in Charles Co into the 1820s, per census records. Any other thoughts/facts about Frederick? It’s a relatively uncommon name among Maddoxes, and a quick search doesn’t bring up many references to him.
I wish I could help you with that one, Eric. I’ve found no Fredericks in my line, and you’re right that the name is unusual. It’s quite possible that he was from the Notley/Samuel Maddox line in St. Mary’s County. I’m finding nothing useful in searches though.