Another tip: I wouldn't give options to the people you're trying to persuade to join in war. You either won't get responses or things will be very hard to put together. Just pick a date, give a format for having players sign up, and always be in command lol. If not it'll be more a joke than anything if you ask me.
Clearly it's an American idea based on the fact that it's the day America won its independence from Great Britain. Just because it isn't important to British people now doesn't mean it isn't a piece of British history.