U-boat campaign
The U-boat campaign from 1914 to 1918 was the World War I naval campaign fought by German U-boats against the trade routes of the Allies. It took place largely in the seas around the British Isles and in the Mediterranean. The German Empire relied on imports for food and domestic food production (especially fertilizer) and the United Kingdom relied heavily on imports to feed its population, and both required raw materials to supply their war industry; the powers aimed, therefore, to blockade one another. The British had the Royal Navy which was superior in numbers and could operate on most of the world's oceans because of the British Empire, whereas the Imperial German Navy surface fleet was mainly restricted to the German Bight, and used commerce raiders and submarine warfare to operate elsewhere.
For the campaign fought during World War II, see Battle of the Atlantic.German U-boats sank almost 5,000 ships with over 12 million gross register tonnage, losing 178 boats and about 5,000 men in combat.[4] U-boats operated in the Atlantic and the Mediterranean, and to a lesser degree in both the Far East and South East Asia, and the Indian Ocean. However, the Allies were able to keep a fairly constant tonnage of shipping available, due to a combination of ship construction and countermeasures, particularly the introduction of convoys.[5]
1916: The High Seas Fleet; Mediterranean, American, Arctic and Black Sea waters[edit]
In support of the High Seas Fleet[edit]
In 1916 the German Navy again tried to use the U-boats to erode the Grand Fleet's numerical superiority; they staged operations to lure the Grand Fleet into a U-boat trap. Because the U-boats were much slower than the battle fleet, these operations required U-boat patrol lines to be set up in advance; then the battle fleet manoeuvred to draw the Grand Fleet onto them.[37]
Several of these operations were staged, in March and April 1916, but with no success. Ironically, the major fleet action which did take place, the Battle of Jutland, in May 1916, saw no U-boat involvement at all; the fleets met and engaged largely by chance, and there were no U-boat patrols anywhere near the battle area. A further series of operations, in August and October 1916, were similarly unfruitful, and the strategy was abandoned in favor of resuming commerce warfare.
The British were well aware of the risk of U-boat traps to the Grand Fleet, although they had no means of knowing where these might lie. However Jellicoe had developed a tactical response to the problem (which, in the event, was never tested). Faced with a German fleet that turned away, he would assume a submarine trap, and decline to follow, but would move at high speed to the flank, before deploying or opening fire; the aim of this would be to fight the battle away from the ground chosen by his enemy, and forcing any U-boats present to surface if they intended to follow.[38]
Mediterranean waters[edit]
During 1916 the commerce war continued in the Mediterranean, albeit under cruiser rules after April 24 due to the Sussex incident. Allied countermeasures were largely ineffective; the complex arrangements for co-operation between the various navies meant a fragmented and unco-ordinated response, while the main remedy favored by the Allies for the U-boat menace, the Otranto Barrage, was of little value.
Just two U-boats were caught in the barrage in all the time it was in operation; meanwhile merchant shipping suffered huge losses. In 1916 the Allies lost 415 ships, of 1,045,058 GRT, half of all Allied ships sunk in all theatres.
Eight of the top dozen U-boat aces served in the Pola flotilla, including the highest scoring commander of all, Lothar von Arnauld de la Perière.
American waters[edit]
In 1916 the Germans completed two submarine merchant vessels, to be used as blockade runners. The aim was to use them to carry high value goods to neutral nations such as the US, which still maintained a strict neutrality, and was prepared to trade with Germany as with any other nation. The first of these vessels, Deutschland, sailed in summer 1916 and made a favorable impact on US public opinion. She made a second equally successful voyage in autumn of that year. Her sister, Bremen, was less fortunate; she disappeared on her maiden voyage, the cause of her loss unknown.
A less favorable impression was made by the cruise of U-53 under K/L Hans Rose. After refuelling at Newport, Rhode Island, Rose raided Allied shipping off the coast of Canada and the United States. Although this was in international waters, and Rose scrupulously followed international law, the action was seen as an affront to the US, particularly when US warships were forced to stand aside while merchant ships nearby were sunk.[39]
Arctic waters[edit]
In autumn 1916, U-boats of the High Seas flotilla attacked shipping bound for Russia. Five U-boats operated in the Barents Sea between North Cape and the Kola inlet. Also, the two UE1-class minelaying boats laid minefields in the White Sea. These boats sank 34 ships (19 of them Norwegian) before winter ice closed the area for operations.
One of the ships sunk near the Norwegian coast was the Romanian merchant Bistrița, sunk by U-43 on 11 November. Before sinking the ship, the captain of the U-boat allowed the ship's crew to take refuge in his submarine, then later he handed over the crew to a Russian sailing ship which took them to Vardø. From there, they were eventually repatriated.[40]
Black Sea waters[edit]
The Constantinople Flotilla was established in May 1915 and operated U-boats in the Black Sea.[41] Bulgaria joined the campaign in May 1916, when the German submarine UB-8 was commissioned by the Bulgarian Navy as Podvodnik.[42] In three years of operation, the Flotilla sank ships totalling 117,093 GRT.[43]
UB-45 was lost in November 1916 and UB-46 in December, both sunk by Russian mines.[44] In addition, UB-7 was reportedly sunk by Russian aircraft in October.[45]
Throughout September and October 1916, the main task of the submarines UB-42 and UB-14 was patrolling the Russian and Romanian coasts, from Constanța to Sevastopol.[46] On 30 September 1916, near the port of Sulina, UB-42 launched a torpedo at the Romanian torpedo boat Smeul, but missed. The Romanian warship counterattacked, damaging the submarine's periscope and conning tower and forcing her to retreat.[47][48][49] In November, the German submarine UC-15 was sent on a minelaying mission off Sulina and never returned, being sunk by her own mines.[50][51] This was probably caused by an encounter with Smeul, whose captain surprised a German submarine near Sulina in November 1916, the latter reportedly never returning to her base at Varna, Bulgaria. This could only be UC-15, whose systems most likely malfunctioned after being forced to submerge in the shallow waters, upon encountering the Romanian torpedo boat.[52]
Internal German debate[edit]
During 1916, continual and fierce debate took place within the German government between advocates and opponents of unrestricted submarine warfare, the latter led by Chancellor Bethmann Hollweg. As the military opposed commerce warfare under cruiser rules, a number of options for an intensified campaign was suggested and in some cases briefly implemented:
In March, Grand Admiral Tirpitz, a key early supporter of submarine warfare, was removed from his post, but the disagreement continued unabated. The Admiralty pushed for no restrictions whatsoever. In particular, after the Sussex Pledge, High Seas fleet commander Scheer adopted an all or nothing approach, refused to contemplate using his submarines in a limited campaign.
However, when Atlantic submarines were finally out into action under cruiser rules in October, they were an immediate success, sinking an average of 350,000 tons per month, over twice what had been managed during unrestricted submarine warfare in 1915. Yet the political tides had begun to shift strongly towards the supporters of an unlimited submarine war.[53]
Japanese participation[edit]
Beginning in April 1917, Japan, an ally of the United Kingdom, sent a total of 14 destroyers to the Mediterranean with cruiser flagships which were based at Malta and played an important part in escorting convoys to guard them against enemy submarines. The Japanese ships were very effective in patrol and anti-submarine activity.[68] However, of the 9 Austro-Hungarian navy submarines lost to enemy action, 5 were sunk by Italian navy units (U-13, U-10, U-16, U-20, and U-23), 1 by Italian and French units (U-30), 1 by Royal Navy units (U-3), while none were sunk by the Japanese navy, which lost one destroyer (Sakaki, torpedoed by U-27).
Brazilian participation[edit]
On 21 December 1917 the British government requested that a Brazilian naval force of light cruisers be placed under Royal Navy control and a squadron comprising the cruisers Rio Grande do Sul and Bahia, the destroyers Paraíba, Rio Grande do Norte, Piauí, and Santa Catarina, and the support ship Belmonte and the ocean-going tug Laurindo Pitta was formed, designated the Divisão Naval em Operações de Guerra ("Naval Division in War Operations"). The DNOG sailed on 31 July 1918 from Fernando de Noronha for Sierra Leone, arriving at Freetown on 9 August, and sailing onwards to its new base of operations, Dakar, on 23 August. On the night of 25 August the division believed it had been attacked by a U-boat when the auxiliary cruiser Belmonte sighted a torpedo track. The purported submarine was depth-charged, fired on, and reportedly sunk by the Rio Grande do Norte, but the sinking was never confirmed.
The DNOG patrolled the Dakar-Cape Verde-Gibraltar triangle, which was suspected to be used by U-boats waiting on convoys, until 3 November 1918 when it sailed for Gibraltar to begin operations in the Mediterranean, with the exception of the Rio Grande do Sul, Rio Grande do Norte, and Belmonte. The Division arrived at Gibraltar on 10 November; while passing through the Straits of Gibraltar, they mistook three USN subchasers for U-boats but no damage was caused.[69]
Aftermath[edit]
By mid-1918, U-boat losses had reached unacceptable levels, and the morale of their crews had drastically deteriorated; by the autumn it became clear that the Central Powers could not win the war.
The Allies insisted that an essential precondition of any armistice was that Germany surrender all her submarines, and on 24 October 1918 all German U-boats were ordered to cease offensive operations and return to their home ports. The Allies stipulated that all seaworthy submarines were to be surrendered to them and those in shipyards be broken up.
More than 160 U-boats surrendered at Harwich, Essex in November 1918. Overseen by Rear Admiral Sir Reginald Tyrwhitt, commanding officer of the Harwich fleet, the German crews were loaded on to transport ships to be sent home without being allowed to set foot on British soil. Some of the U-boats were sent to places such as Liverpool or Brighton to be put on display whilst others were left on the beach.[70]
The last significant role played by U-boats in World War I was the suppression of the German naval mutiny that same month, when they stood ready to "fire without warning on any vessel flying the red flag".[71]
Grand Total 12,850,815 gross tons
Allied losses included 10 battleships, 18 cruisers and several smaller naval vessels.[72]
Unrestricted submarine warfare was resumed in February 1917 and the British began full-scale convoying in September 1917. The heaviest losses were suffered in April 1917 when a record 881,027 tons were sunk by the U-boats.[73]
150,000 tons of purely British shipping were lost in January 1917, and 300,000 tons in February; Allied and neutral losses increased in a similar proportion. In April 525,000 tons of British shipping were lost. In October 270,000 tons were lost, and in December 170,000 tons were lost. These totals are included in the above figures.[74]
29 U-boat commanders were decorated with the Pour le Mérite, the highest German decoration for gallantry for officers.[75] 12 U-boat crewmen received the Goldene Militär-Verdienst-Kreuz, the highest bravery award for non-commissioned officers and enlisted men.[76]
The most successful U-boat commanders of World War I were Lothar von Arnauld de la Perière (189 merchant vessels and two gunboats with 446,708 tons), followed by Walter Forstmann (149 ships with 391,607 tons), and Max Valentiner (144 ships with 299,482 tons).[77] So far, their records have never been surpassed by anyone in any later conflict.
Sir Joseph Maclay, the British Minister of Shipping, approved four standard designs of merchant ship and placed orders for over 1,000,000 tons of shipping (Britain launched 495,000 tons of shipping in the first half of 1917, but 850,000 tons were sunk in the first quarter alone; by 1918 3,000,000 tons a year were being launched).[78]
According to Clodfelter's encyclopedia of military casualties: [72]
Other sources give different numbers, however, as by the nature of submarine warfare, frequently u-boats simply disappear on patrol and the cause must be pieced together from the location they sunk, reported engagements by the allies, or wreck data if found. Uboat.net's listing of u-boat fates gives[79]