First World War Maritime Archaeology

Britain on the Brink of Starvation: Unrestricted Submarine Warfare

On 1 February 1917, Germany resumed its policy of ‘unrestricted submarine warfare.’

The seas around the British Isles were declared a war zone in which fishing vessels and unarmed merchant vessels, carrying essential items such as foodstuffs, coal and iron ore, would be attacked without warning by German U-boats.

Prior to this a U-boat would surface, search a vessel, give the crew time to take to lifeboats and then sink the vessel by gunfire or torpedo.

Now there were numerous indiscriminate deadly attacks, with ships sunk as soon as they were spotted.

A photograph of a cigarette card showing a captain behind the wheel of a ship.
Will’s cigarette card from the First World War. © Mark Dunkley.

By April, the Allies were suffering appalling losses. An average of 167 merchant ships were being sunk by U-boats every month.

By August 1917, 40,860 merchant seamen, fishermen and passengers, along with 4,696 ships had been lost. Britain was near starvation with only 6 weeks of food left.

At one stage, only four days’ supply of sugar remained and a few weeks’ worth of flour. Long queues in the shops and rising prices led to compulsory rationing in December 1917.

A photograph of a war medal featuring the wording 'For war service Mercantile Marine, 1914 - 1918'.
A Mercantile Marine war medal. Sailors in the Merchant Navy were awarded the medal if they had made one or more voyage through a war zone or danger zone during the course of the war. © Wayne Cocroft.

The German navy had initially introduced unrestricted submarine warfare early in 1915. Britain was heavily reliant on foodstuffs and munitions carried across the Atlantic from Canada and neutral America in merchant ships.

Attacking these vessels offered huge opportunities for Germany to bring Britain to her knees through starvation, but brought with it the risk of America entering the war.

A photograph of the rusting tower of a submarine.
The conning tower of U-20 which torpedoed the liner Lusitania. On display at the Strandingsmuseum St. George, Denmark. © Erik Larson.

On 7 May 1915 the U-boat, U-20, torpedoed the British liner RMS Lusitania off Ireland during its passage from New York to Liverpool.

A poster of a ship under attack with the wording 'Irishmen avenge The Lusitania.  Join an Irish regiment today.'
A highly emotive recruiting poster published following the sinking of the Lusitania. © Crown Copyright.

Although the ship was later confirmed to be carrying munitions for the war effort, it was principally a passenger ship.

Of the 1,900 passengers and crew members on board, 1,198 died. The sinking sent shock waves round the world and was used as a recruiting tool by the British government.

Among the dead were 128 Americans. Outraged, the US President Woodrow Wilson demanded an end to German attacks against unarmed merchant ships.

Within four months, again for fear of America entering the war, the German government had imposed such strict constraints on U-boat operations that the German navy suspended the policy.

A black and white photograph of a naval battle.
Battle of Jutland: HMS Invincible suffering a fatal direct hit 31 May 1916. Courtesy of the National Museum of the Royal Navy. Appears in IWM collections.

The Battle of Jutland (31 May to 1 June 1916) showed that the German Navy was not strong enough to defeat the Royal Navy in a head-on battle.

A poster showing a depiction of Kaiser Wilhelm II with ships in the background. The text says 'Defeat the Kaiser and his U-boats.'
British First World War propaganda poster circa 1917.  Image courtesy the U.S. Library of Congress.

In the aftermath, German naval commanders argued for a more offensive use of submarines, claiming that the U-boat should become an essential component of their war strategy.

Germany’s U-boat fleet had been considerably enlarged in 1916 so there was confidence in the weapon’s potential for success and victory.

In addition, the sea-borne supply of coal and ore to the Allies for munitions manufacture could be seriously interrupted, and the poor wheat harvest of 1916, which was causing the Allies food shortages, could be made worse through U-boat attacks on trans-Atlantic food supplies.

There was also tremendous pressure from a hungry and frustrated German public. Unrestricted submarine warfare resumed on 1 February 1917.

A black and white photograph of a convoy of ships.
Convoy approaching Brest, North-West France, 1918. © Robert W. Neeser.

Faced with terrible merchant shipping losses from resumed U-boat attacks, the British government finally decided on 24 May 1917 to adopt the convoy system for merchant ships, with vessels sailing together, protected by Royal Navy destroyers.

A black and white photograph of a ship painted in camouflage.
A vessel painted in ‘razzle-dazzle camouflage’. © Image courtesy WDC.

Dazzle ships were also employed, designed to break up a vessel’s contours, making targeting, range-finding and speed calculations more difficult for U-boats.

Shipping losses began to decline. The German U-boat gamble was neutralised.

When the United States entered the war on 6 April 1917, partly as a consequence of the unrestricted submarine warfare strategy, the ultimate defeat of Germany became inevitable.

Further reading

6 comments on “Britain on the Brink of Starvation: Unrestricted Submarine Warfare

  1. In this history of the First World War, Canada gave tremendously to the effort, feeding Britain and supplying an important portion of its amunition. A recognition not always given.

  2. Ireland has never been part of Great Britain. It was part of the United Kingdom.

  3. Ken Hamilton

    Great article, but the photo of HMS Invincible is a fake – it is a peacetime photo of HMS Invincible, with the explosion and a couple of extra ships painted on. The explosion of the forward cordite magazine, which should vent through the forward turret is shown as occurring in the wrong place. This does not detract from the article, though!

    • Hi Ken, thanks for your comment. You’re right- the photo has been heavily retouched. It appears in the Imperial War Museums collection here:
      Enhancement, as you’ve mentioned, was primarily used for publications.
      We can guess in this case that the context was probably either that an existing photo was placed in a war context for illustration or that a real-life photo from the battle was retouched.
      I’ve added a link to the IWM page in the image caption for clarity.

  4. Martin Thompson

    The USA entering the war didn’t make victory inevitable. They didn’t reach the battlefield in significant numbers until June 1918. With Russia out of the war, the Germans nearly won with their Spring offensive in March 1918.

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