The controversial 1619 Project has a documentary out that makes the claim that Lord Dunmore's 1775 proclamation was actually the catalyst that prompted the Revolutionary War
Specifically, they are there to talk about John Murray, the Earl of Dunmore, who was Virginia’s colonial governor during the American Revolution. In 1775, Dunmore issued a proclamation that, among other things, declared that any enslaved person who fought on behalf of Britain against the colonists would be granted their freedom — a proclamation that “infuriated White Southerners,” Holton says.
“So,” Hannah-Jones replies, “you have this situation where many Virginians and other Southern colonists, they’re not really convinced that they want to side with the patriots, and this turns many of them toward the revolution, is that right?”
“If you ask them, it did. The record is absolutely clear,” says Holton, a professor of early American history at the University of South Carolina. “I can’t think of a point that I could make about the American Revolution where I could compile as many quotes as I can from White Southerners saying how furious they are.”
I have no doubt this helped tip some scales for those who owned slaves, but were not yet ready to commit to revolution. The counter-argument is that there's a fairly long list of reasons for them to have already been upset with Britain. The 1619 Project makes this out to be a primary driver of Revolutionary sentiment. How much impact did it really have?