What Were the Liberty Ships and How Did They Help Win the Second World War? | History Hit

What Were the Liberty Ships and How Did They Help Win the Second World War?

John Henshaw

Twentieth Century World War Two
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The Battle of the Atlantic was the longest single battle of World War Two, from the very first day, 3 September 1939, to the German Surrender on 7 May 1945.

In this period – 2,073 days or 5 years and 8 months – a total of some 27.5 million tons of merchant shipping were sunk in the Atlantic Ocean, mainly by German U-boats. All wars are a battle of logistics and none more-so than this.

Britain stands alone

From the French surrender on 25 June 1940 until 7 December 1941 when the Japanese attacked the United States at Pearl Harbour, Britain stood alone.

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Dependent on seaborne lines of communications, from her Empire and from America, ships were being sunk at a faster rate than they could be replaced.

If that had continued then the result was inevitable – an inability to prosecute the war and to feed its own people. Ultimately, a negotiated peace with Germany or surrender.

Cyril Thompson’s mission

In September 1940, a relatively young man, Cyril Richard Thompson (33) from an old established shipbuilding company located on the banks of the River Wear in Sunderland, England, was commissioned by the British Government to head a mission to America to order 60 tramp ship types to a design that Thompsons had developed progressively in 1934-1940.

Tank testing had proved that a fuller entry, a raked bow, finer lines leading into the stern post with a cruiser stern plus a semi-balanced rudder offering less drag produced a ship that, when coupled with an improved Vertical Triple Expansion engine (VTE) with a re-heater and developing a modest 1,500 IHP, used only 16-17 tons per day instead of the customary 25 tons at 10 knots for a ship of that size and tonnage.

None of these improvements were entirely new but it was Cyril Thompson who put them together in one package as SS Embassage in 1935.

The success of Embassage led to a larger SS Dorington Court version of 1939 and an even larger SS Empire Wind series in 1940 for the British Ministry of War Transport (as it became).

Thompson took the Empire Liberty plans with him to America but shipbuilders were too busy with orders from the United States Maritime Commission (which were larger, faster and more sophisticated merchant ships) to consider adding 60 more ships to a design they were not familiar with.

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Henry J. Kaiser’s shipyards

However, the enterprising Henry J. Kaiser took on the challenge with two specifically-built shipyards: Richmond, California and Portland, Maine.

But, instead of the favoured British method which was for the more skillful but slower riveted construction, the ships were to be predominately of welded construction – a method the British shipyards had yet to fully embrace.

Accordingly, the British plans had to be substantially altered and, more particularly, expanded in details as British shipyards were used to working with what was, by American standards, minimal documentation because they were essentially repeating what had been unchanged for generations.

What did not change were the basic lines that affected the hydrodynamics and the machinery. These 60 ships became known as the Ocean Class.

Production under Roosevelt’s orders

President Franklin D. Roosevelt was prescient when he determined in January 1941 that despite the best efforts of the USMC and American shipyards, insufficient tonnage was going to be available and that America needed to build ships of the type the British had ordered.

Despite resistance – the objectors claiming that ships good for 11 knots and 5 years of service was not what the American merchant marine needed and that bigger, faster and 20-year ships better met their long-term needs – an order was placed for what Roosevelt claimed to be “ugly ducklings”.

However, these were to be of welded construction and oil-fired with water-tube boilers instead of coal-fired with Scotch boilers and with the cheap and easy-to-produce VTE propulsion.

Line drawing of a Liberty Ship (Credit: Kallgan / CC BY-SA)

The naval architects Gibbs & Cox kept the basics unaltered but changed the superstructure from a two-island one to a single island to bring the crew together into one area and made small changes to suit specific American requirements and shipbuilding practice.

Despite what was basically an adaptation of an existing design where all the ingenuity and hard work had been Thompsons between 1935 and 1940, Gibbs & Cox still maintain that the 2,710 Liberty Ships that were launched were to their design.

To rightfully claim this, in my opinion, they would have to have started with a clean sheet of paper – not sets of drawings that reflected over five years of development so much so that a complete set of full-sized templates of SS Empire Liberty’s hull shape at the various stations was made available thus saving considerable time and effort.

Role of the Liberty ships

The kudos for building the Liberty ships belongs rightly with America. The kudos for inventing the basics, for designing the hull and propulsion combination, belongs to Britain.

Slow, ugly (in some eyes) and unsophisticated, the Liberty ships more than delivered what they promised.

With the expectation that one successful trans-Atlantic voyage with some 10,000 tons of cargo of any sort justified its construction, anything else was a bonus. And bonuses they delivered in great measure.

Many found themselves in USN service in a wide variety of uses: tankers, distilling ships, maintenance ships, mule transports, troop transports and hospital ships.

The Battle of the Atlantic meant near constant fear for merchant seamen.

Defying all critics, during the Cold War Liberty ships were converted to early-warning spy ships with a plethora of sophisticated detection equipment and to guided missile range ships – the last of which was decommissioned in 1966.

One, built to the British model in a Canadian shipyard, served in the Royal Navy as a guided-missile test ship.

Others, built in Britain to the same basic model but diesel-engined, served in World War Two as Merchant Aircraft Carriers (MAC), accompanying convoys carrying a load of grain while providing anti-submarine coverage to the point where not one merchant ship was lost in a convoy where a MAC was present.

Without doubt, the Liberty ships played a hugely important role in the logistics of warfare, both in the Atlantic and the Pacific.

There are those who say the Liberty ships won the war. This is an over-reach – many steps too far. No ships, as such, won the Second World War or, indeed, secured a victory.

The British-derived Liberty ship should take its place with other iconic war-winning American-produced weapons as the M1 Garand rifle, the Willys Jeep, the Douglas Dakota, the Fletcher Class destroyer, the North American P 51 Mustang fighter – to mention but a few.

John Henshaw is a retired chartered surveyor, accompished marine watercolour painter and ship modeller and a fine technical draughtsman. His beautiful linework is a highlight of this book, ‘Liberty’s Provenance: The Evolution of the Liberty Ship from its Sunderland Origins’ , which was published on 7 May 2019 by Pen and Sword.

John Henshaw