The Continental Congress authorized the building of this 54 foot, 29–ton gunboat and eight other similar vessels for the defense of the Champlain Valley – the northern frontier of the colonies considered the key to the success or failure of the American Revolution. In the summer of 1776, Philadelphia and her sister–ships were hurriedly organized into what historians consider "the first American Navy."

Throughout the summer and into the fall, this small fleet imposed a strategic delay on British invasion plans to divide the colonies. In October of 1776, the superior firepower of the British squadron proved decisive and the badly–damaged Philadelphia sank. Though a defeat for the Americans, the naval contest for Lake Champlain gave the American army time to build the strength necessary for the victory at Saratoga.

The Philadelphia rested on the bottom of the lake until it was discovered and recovered with much of its equipment intact in 1935, and it came to the Smithsonian’s National Museum of American History in 1964, complete with the 24–pound ball that sent the gunboat to the bottom.