The Green Mountain Boys Flag was carried by militia members from an area between the New York and New Hampshire colonies called the New Hampshire Grants. This would eventually become the State of Vermont, which joined the United States as the 14th state in 1791.
The Green Mountain Boys formed their militia group to protect their land grants from attempts by New York to control their land. New Hampshire had given local settlers the land grants. In a legal dispute, the land was officially given to New York by the British government.
New York made various attempts to settle the area and to enforce the law, but Ethan Allen and his Green Mountain Boys successfully repelled them. They were made up of a group of settlers consisting of many friends and family members. After the Declaration of Independence was declared the area declared itself not only independent from Great Britain, but an independent republic the Vermont Republic.