STATISTICS can be used to argue all manner of conclusions about the First World War but often don’t paint the full picture.

This became obvious from a lecture at Barrow’s Forum on Wednesday night when naval historian Prof Eric Grove was the guest of South Cumbria’s combined engineering groups.

His topic was the German U-boat Crisis of 1917 – which turned out to be far from the potential war-changing event it has often been portrayed as.

In April 1917 Germany’s unrestricted U-boat campaign sank 881,027 tons of shipping from allied and neutral nations but record amounts of food was still arriving in Britain.

April to June 1917 saw a wartime high of 1.77m tons of wheat and flour arrive.

The secret was not how many ships were lost but how well the rest were used.

Sir Arthur Salter at the Ministry of Shipping took over control of all British merchant shipping and was able to force other nations to follow his instruction through control of coal supplies.

Prof Grove said: “The problem was solved by redirecting traffic on to the North Atlantic Run.”

Canada and the United States provided much of the food needed to keep Britain in the war and kept ships away from U-boats operating out of Zeebrugge and Ostende.

He said: “Ships are being sunk, sailors are dying, but goods continue to arrive.”

Some indivual U-boat commanders had remarkable successes in terms of the number of ships sunk – but many of them were old and small.

Trawlers and even sailing ships were as likely to be attacked as big, modern steam-powered cargo ships.

And there were plenty of targets as the British Merchant Navy dominated the world shipping trade with more than half of all the ships above 3,000 tons.

The U-55 sank 25,000 tons of shipping on its 14 patrols, including the Carpathia which had rescued the survivors of the Titanic.

He said: “It was one of the most effective of the German submarines.”

The UB-40 made 28 patrols and sank 100 vessels. The U/C class of submarine had torpedo tubes and was also a mine layer.

Just 64 of them managed to sink 1,800 ships.

He said: “They were remarkably effective little boats.”

The German aim was sink 600,000 tons of shipping per month and this was achieved as an average for several months in 1917 – but was still not enough to starve Britain.

Ship losses gradually fell towards the end of the war as armed ships gave protection to cargo ships sailing in convoys and intercepted German messages gave convoys more chance to avoid U-boats.

He said: “The Germans failed miserably to force Britain into some form of negotiated truce.”