The ensign is the Serapis flag which was an early US Navy ensign of Cpt John Paul Johns, and arguably one of the first internationally recognised US flags (although ironically enough not by congress!) I used this rather than the continental colours as the thirteen colonies flag is based on that. The war flag is based on US regimental flags in the late 18th/early 19th century. Like the game I used the Betsy Ross flag as the state flag.
Before that it is an unplayable emergent faction from the Thirteen Colonies which I will get to later.
The USA is only available as a playable quest after you complete the 'road to independence' campaign.
