By 1914 the submarine was not a new weapon, having first been used 150 years earlier. By the start of WW1 all the major powers possessed submarines, but their role was still undefined. Were they long range patrol craft for the battle fleets, or were they a strike force to be used against enemy warships? Or, as British Admiral Scott wrote just before the advent of WW1, could they be used as a weapon to destroy a nations shipborne commerce?
Were the Unterseeboots Ready for War?
U-boats were the submarine arm of the German navy and a month into WW1 they struck at the Royal Navy when U-21 sank the cruiser HMS Pathfinder. This was the first successful use of a self-propelled torpedo. Three weeks later U-9 sank three British cruisers in less than one hour. The German high command realised that they had a major new weapon for waging maritime warfare. On 20th October 1914 the first merchantman was sunk by U-17 observing Prize Rules, which required warning and humane treatment of the crew.
Within three months the whole nature of naval warfare had changed. The mighty Royal Navy was reluctant to expose its capital ships to this new menace while the German fleet generally stayed in anchorage at Wilhelmshaven. The focus turned to economic warfare, with Britain and France blockading Germany and the U-boats attempting to deprive Britain of vital imports.
How Large Was the First U-boat Fleet?
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Sign up to our Free Weekly NewsletterAt the start of the war the Kriegsmarine had 29 operational submarines, although some of these were small, petrol engine ships, and 25 under construction. However, in the right hands they were still deadly weapons as demonstrated by U-9, above. Later ships, like U-21, were diesel powered with longer range and more torpedoes. There were also large numbers of coastal submarines, prefixed UB and minelaying submarines, prefixed UC. To help break the economic blockade eleven U-Cruisers were built, with long range and cargo carrying capacity. By the end of the war 375 submarines were commissioned and 178 were lost with most of the rest surrendering in British ports after the Armistice.
How Close Were the U-boats to Success?
This was a new type of warfare, targeting civilians at sea and at home. Unrestricted submarine warfare against neutrals was first applied, abandoned in September 1915, due to fear of angering the USA, and finally resumed in February 1917. Warfare targeting an economy was not new but the application of it by submarines was, especially after the area around Britain and Ireland was declared a War Zone. By the end of 1917 U-boats had sunk 30% of the worlds merchant shipping.
The convoy system was introduced in September 1917 and this led to a reduction in sinkings. This and the increasing involvement of the USA in the war led to a continuing decline in losses. Despite many individual successes the campaign had failed.
U-boats Under the Swastika
Germany was forbidden to possess submarines after the Versailles treaty in 1919. In the early 1920’s some submarines were secretly built overseas and after the Anglo-German Naval Treaty in 1935 U-boats were openly developed. The workhorse of the submarine fleet was the Type VIIC and over 700 were built. The later ships (Types IX and XXI) possessed a greater range, allowing the ships to spend longer in action. They could also submerge to a greater depth, giving them a better chance of avoiding detection and destruction.
As Allied air power increased U-boats were often fitted with anti-aircraft guns, either one 3.7cm or quadruple 2cm. Other additions included a schnorkel, enabling the submarine to ‘breath’ and stay submerged, although only at periscope depth. Antenna that could detect the use of radar on enemy aircraft, thus giving the submarine time to submerge, were also fitted after mid-1942.
What Was the Elite Arm of the Kriegsmarine?
Under Admiral Dönitz the U-boats were developed as an elite fighting force. He was a submarine commander in WW1 and realised how close this weapon had come to defeating Britain. He thought that with the right tactics and sufficient U-boats they could sink enough ships to force Britain to sue for peace. At the start of the war Germany possessed only 57 U-boats, far below the 300 that Dönitz deemed necessary to sink a million tons a month which he believed would defeat Britain. New tactics included U-boats grouped in ‘Wolf Packs’, directed by Luftwaffe long-range reconnaissance aircraft. The U-boats waged war relentlessly, sinking Allied ships on the first and last days of the European war.
How Close to Success Were the U-boats?
The short answer is that it ended in a similar way as in WW1. Once again, the U-boat arm sank vast numbers of merchant shipping, 14.7 million tons in this war, compared to 11.1 million in WW1. It was not until mid-1943 that it was apparent that the Allies were winning, with the inexorable application of US military and industrial might. As in WW1 the U-boats had fought both ruthlessly and heroically in a losing cause.
