(https://www.dreadnoughts.ultimateadmiral.com/the-playing-modes)
As I understand explanation on the official website: Game will start historically (historicall accurate territories etc.) in the year that you choose (1890, 1900, 1910, 1920 or 1930) and than it depends on you. You can continue historically but you don't have to. Anyway it's not stated if AI will try to act historically.