John Merrywater was an American (Texan) General during the Conquering.
Merrywater was a military genius. He was inspired by the campaigns of the ancient general Hannibal as he planned the counter-attack of the American forces to smash the rebellious Golds.
His forces attacked Luna with a mech battalion and destroyed the first line of defense with their railguns, but the resistance on Luna itself was stiffer than expected. Merrywater's flagship, the Davy Crocket, was heavily damaged and crashed into the Atlas Mountains on Luna, killing the entire crew. 
- Comics Beat - INTERVIEW: Pierce Brown chats about expanding his Red Rising universe, https://www.comicsbeat.com/interview-pierce-brown-red-rising/ - September 20, 2019