U-boat campaign prompted US entry

The U-boat SM UC-45 was credited with sinking 12 ships, including the Eganaes, with torpedoes and mines but sank in a diving accident on September 12 1917.

Although she was raised and re-entered into service, the boat was surrendered following Armistice and promptly broken up.

The entry of the United States into the First World War is largely attributed to the U-boat campaign of early 1917.

In early 1915, following the sinking of the liner Lusitania, Germany had stopped its unrestricted submarine warfare in the Atlantic because of concerns of drawing the United States into the conflict.

But with the growing discontent of the German public due to the food shortages, however, the government resumed unrestricted submarine warfare in February 1917.

They had calculated that a successful submarine and warship siege of Britain would force that country out of the war within six months, while American forces would take a year to become a serious factor on the Western Front.

Picture: Getty Images. U-boats lined up in Kiel harbour, Germany, during the First World War.