In October 1775, the Continental Army besieging Boston was in desperate need of supplies, primarily gunpowder. From spies in England, Continental Congress learned of supply ships that traveled regularly from London to Nassau in the Caribbean and authorized the purchase and outfitting of two ships to capture them. They purchased the Philadelphia merchantman, Black Prince, from Continental Congressman Robert Morris on 13 October (birthday of the US Navy), renamed her the Alfred, and outfitted her as a ten gun sloop-of-war.
To differentiate American warships from British warships, the 13 Colonies needed a flag. In November, Continental Congress adopted the red British Ensign with the addition of 13 white stripes on the red field and called it the Grand Union Flag. The optimistic thinking behind the design was that it allowed American crews of captured British vessels the ease of creating a new flag to fly over their prize by just sewing white stripes on the captured British ensigns. In any case, it was the first American national flag, and it was raised for the first time on 3 December 1775 at the commissioning ceremony of the Alfred. LTG George Washington would raise the Grand Union Flag for the first time at the Continental Army encampment outside Boston on New Year’s Day 1776.