World War II: The Liberty Ship Program

Liberty Ship SS John W. Brown
National Archives & Records Administration

The origins of the Liberty Ship can be traced to a design proposed by the British in 1940. Seeking to replace wartime losses, the British placed contracts with US shipyards for 60 steamers of the Ocean class. These steamers were of simple design and featured a single coal-fired 2,500 horsepower reciprocating steam engine. While the coal-fired reciprocating steam engine was obsolete, it was reliable and Britain possessed a large supply of coal. While the British ships were being constructed, the US Maritime Commission examined the design and made alterations to lessen coast and speed construction.


This revised design was classified EC2-S-C1 and featured oil-fired boilers. The ship's designation represented: Emergency Construction (EC), a length of 400 to 450 feet at the waterline (2), steam-powered (S), and design (C1). The most significant change to the original British design was to replace much of the riveting with welded seams. A new practice, the use of welding decreased labor costs and required fewer skilled workers. Possessing five cargo holds, the Liberty Ship was intended to carry a cargo of 10,000 longs tons (10,200 tons). Featuring deck houses amidships and aft, each vessel was to have a crew of around 40 sailors. For defense, each ship mounted a 4" deck gun atop the after deck house. Additional anti-aircraft defenses were added as World War II progressed.

The attempt to mass-produce ships using a standardized design had been pioneered during World War I at the Emergency Fleet Corporation's Hog Island Shipyard in Philadelphia, PA. While these ships, arrived too late to impact that conflict, the lessons learned provided the template for the Liberty Ship program. As with the Hog Islanders, the Liberty Ships' plain looks initially led to a poor public image. To combat this, the Maritime Commission dubbed September 27, 1941, as "Liberty Fleet Day" and launched the first 14 vessels. In his speech at the launch ceremony, Pres. Franklin Roosevelt cited Patrick Henry's famed speech and stated that the ships would bring liberty to Europe.


In early 1941, the US Maritime Commission placed an order for 260 ships of the Liberty design. Of these, 60 were for Britain. With the implementation of the Lend-Lease Program in March, orders more than doubled. To meet the demands of this construction program, new yards were established on both coasts and in the Gulf of Mexico. Over the next four years, US shipyards would produce 2,751 Liberty Ships. The first ship to enter service was SS Patrick Henry which was completed on December 30, 1941. The final ship of the design was SS Albert M. Boe which was finished at Portland, ME's New England Shipbuilding on October 30, 1945. Though Liberty Ships were constructed throughout the war, a successor class, the Victory Ship, entered production in 1943.

The majority (1,552) of Liberty Ships came from new yards built on the West Coast and operated by Henry J. Kaiser. Best known for building the Bay Bridge and the Hoover Dam, Kaiser pioneered new shipbuilding techniques. Operating four yards in Richmond, CA and three in the Northwest, Kaiser developed methods for prefabricating and mass-producing Liberty Ships. Components were built all across the US and transported to shipyards where the vessels could be assembled in record time. During the war, a Liberty Ship could be built in about two weeks at a Kaiser yard. In November 1942, one of Kaiser's Richmond yards built a Liberty Ship (Robert E. Peary) in 4 days, 15 hours, and 29 minutes as a publicity stunt. Nationally, the average construction time was 42 days and by 1943, three Liberty Ships were being completed each day.


The speed at which Liberty Ships could be constructed allowed the US to build cargo vessels faster than German U-boats could sink them. This, along with Allied military successes against the U-boats, ensured that Britain and Allied forces in Europe remained well-supplied during World War II. Liberty Ships served in all theaters with distinction. Throughout the war, Liberty Ships were manned members of the US Merchant Marine, with gun crews provided by the US Naval Armed Guard. Among the notable achievements of the Liberty Ships was SS Stephen Hopkins sinking the German raider Stier on September 27, 1942.


Initially designed to last five years, many Liberty Ships continued to ply the seaways into the 1970s. In addition, many of the shipbuilding techniques employed in the Liberty program became standard practice across the industry and are still used today. While not glamorous, the Liberty Ship proved vital to the Allied war effort. The ability to build merchant shipping at a rate faster than it was lost​ while maintaining a steady stream of supplies to the front was one of the keys to winning the war.

Liberty Ship Specifications

  • Displacement: 14,245 tons
  • Length: 441 ft. 6 in.
  • Beam: 56 ft. 10.75 in.
  • Draft: 27 ft. 9.25 in.
  • Propulsion: Two oil-fired boilers, triple-expansion steam engine, single screw, 2500 horsepower
  • Speed: 11 knots
  • Range: 11,000 miles
  • Complement: 41
  • Stern-mounted 4 in (102 mm) deck gun, a variety of anti-aircraft armament
  • Capacity: 9,140 tons

Liberty Ship Shipyards

  • Alabama Drydock and Shipbuilding, Mobile, Alabama
  • Bethlehem-Fairfield Shipyard, Baltimore, Maryland
  • California Shipbuilding Corp., Los Angeles, California
  • Delta Shipbuilding Corp., New Orleans, Louisiana
  • J. A. Jones, Panama City, Florida
  • J. A. Jones, Brunswick, Georgia
  • Kaiser Company, Vancouver, Washington
  • Marinship, Sausalito, California
  • New England Shipbuilding East Yard, South Portland, Maine
  • New England Shipbuilding West Yard, South Portland, Maine
  • North Carolina Shipbuilding Company, Wilmington, North Carolina
  • Oregon Shipbuilding Corporation, Portland, Oregon
  • Richmond Shipyards, Richmond, California
  • St. Johns River Shipbuilding, Jacksonville, Florida
  • Southeastern Shipbuilding, Savannah, Georgia
  • Todd Houston Shipbuilding, Houston, Texas
  • Walsh-Kaiser Co., Inc., Providence, Rhode Island
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Your Citation
Hickman, Kennedy. "World War II: The Liberty Ship Program." ThoughtCo, Jul. 31, 2021, Hickman, Kennedy. (2021, July 31). World War II: The Liberty Ship Program. Retrieved from Hickman, Kennedy. "World War II: The Liberty Ship Program." ThoughtCo. (accessed February 5, 2023).