Liberty Fleet Day was first observed on 27 September 1941, the day that 14 merchant ships were launched in shipyards across the United States under the Emergency Shipbuilding program. Among the ships launched was the first Liberty ship, SS Patrick Henry. Some of the merchant ships were subsequently converted to other purposes, including as troop transports and a Royal Navy aircraft carrier. In addition to the merchant ships launched, the US Navy launched two destroyers at the Boston Navy Yard.
President Franklin D. Roosevelt launched the first liberty ship, SS Patrick Henry, at the yards of Bethlehem Steel, Baltimore, Maryland, giving a speech as he did so. 27 September became known as Victory Fleet Day during the United States' participation in World War II.