The History of the Pine Tree flag: The Pine Tree flag was in use 1775-1777. It was officially adopted by the Massachusetts Navy in April 1776. It flew over the floating batteries which sailed down the Charles River to attack British-held Boston. This flag is the jack form of the “Bunker Hill” flag. On October 20, 1775, Colonel Joseph Reed, Washington’s military secretary, recommended that this flag be put into general usage so that American ships could recognize one another. The “Pine Tree Flag” is a generic name for a number of flags used by Massachusetts and by New England from 1686 to 1776.