Answer;
It was a political propaganda term used by Paul Revere in the etchings he created after the incident.
Explanation;
When Paul Revere first began selling his color prints of "The Bloody Massacre perpetrated in King Street" in Boston, he was doing what any like-minded patriot with his talents in 1770 would have done. He did it faster and more expeditiously than anyone else, including two other artist-engravers who also issued prints of the Massacre that year.