U-boat Campaign (World War I)

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Battle of the Atlantic
Part of World War I
Date 28 July 1914 – 11 November 1918 Location Atlantic Ocean, North Sea Result Decisive Allied Victory
Belligerents
Royal Navy  Royal Canadian Navy United States Navy  French Navy Imperial Japanese Navy Brazilian Navy	Kaiserliche Marine
Commanders
Lord Fisher Sir Henry Jackson Sir John Jellicoe Sir Rosslyn Wemyss	Friedrich von Ingenohl Hugo von Pohl Reinhard Scheer

v • d • e Theatres of World War I European Balkans – Gallipoli – Western Front – Macedonian Front – Eastern Front – Italian Front Middle Eastern Caucasus – Mesopotamia – Sinai and Palestine – Persia – Arab Revolt African South-West Africa – West Africa – East Africa – North  Africa Asian and Pacific Other Atlantic Ocean – Mediterranean – Naval – Aerial

v • d • e North Sea 1914–1918 Battle of the Atlantic – 1st Heligoland Bight – Live Bait Squadron - Texel – Yarmouth Raid – Scarborough Raid – Dogger Bank – Bombardment of Yarmouth – Jutland – Action of 16 March 1917 – Dover Strait – 2nd Heligoland Bight – Zeebrugge – 1st Ostend – 2nd Ostend

v • d • e The Command of the Oceans, 1914-1915 Papeete – Penang – Coronel – Cocos – Falkland Islands – Más a Tierra – Rufiji Delta - Madras

The U-boat Campaign (World War I) (1914–1918) was the World War I naval campaign fought by German U-boats largely in the seas around the British Isles and in the Atlantic Ocean.

Both the German Empire and United Kingdom relied heavily on imports to feed their population and supply their war industry, thus both aimed to blockade each other. The British had the Royal Navy which was superior in numbers and could operate within the British Empire, while the German Kaiserliche Marine surface fleet was mainly restricted to the German Bight, and used commerce raiders and unrestricted submarine warfare to operate elsewhere.

The successful blockade of Germany contributed to its military defeat in 1918, and, still in effect, enforced the signing of the Versailles Treaty in mid-1919.

Contents 1 Initial campaign 1.1 First German war patrol 1.2 First successes 1.3 First attacks on merchant ships 2 Unrestricted submarine warfare 2.1 RMS Lusitania 2.2 Submarine minelayers 2.3 SS Arabic 2.4 Depth charges 3 Mediterranean U-boat campaign 4 Resumption of unrestricted submarine warfare 4.1 Allied response 5 American campaign 6 Japanese participation 7 Brazilian Participation 8 The end 9 Summary 9.1 Allied and Neutral Tonnage sunk by submarines in World War I 9.2 German Submarine Force 1914-1918 10 Notes 11 References 12 External links

[edit] Initial campaign

[edit] First German war patrol

On 6 August 1914, two days after Britain had declared war on Germany, the German U-boats U-5, U-7, U-8, U-9, U-13, U-14, U-15, U-16, U-17, and U-18 sailed from their base in Heligoland to attack Royal Navy warships in the North Sea in the first submarine war patrol in history.^[1]

The U-boats sailed north, hoping to encounter Royal Navy squadrons between Shetland and Bergen. On 8 August one of U-9's engines broke down and she was forced to return to base. On the same day, off Fair Isle, U-15 sighted the British battleships HMS Ajax, Monarch, and Orion on manoeuvres and fired a torpedo at Monarch. This failed to hit, and succeeded only in putting the battleships on their guard. At dawn the next morning, the 1st Light Cruiser Squadron, which was screening the battleships, came into contact with the U-boats, HMS Birmingham sighting U-15, which was lying on the surface. There was no sign of any lookouts on the U-boat and sounds of hammering could be heard, as though her crew were performing repairs. Birmingham immediately altered course and rammed U-15, cutting her in two.

On 12 August seven U-boats returned to Heligoland; U-13 was also missing, and it was thought that she had struck a mine. While the patrol was a failure, it caused the Royal Navy some uneasiness in that it proved false earlier estimates as to U-boats' radius of action and left the security of the Grand Fleet's unprotected anchorage at Scapa Flow open to question. On the other hand, the ease with which U-15 had been destroyed by HMS Birmingham encouraged the false belief that submarines were no great danger to surface warships.

[edit] First successes

On 5 September 1914, U-21 commanded by Lieutenant Otto Hersing made history when he torpedoed the Royal Navy light cruiser HMS Pathfinder. The cruiser's magazine exploded, and the ship sank in four minutes, taking 259 of her crew with her. It was the first combat victory of the modern submarine.

The German U-boats were to get even luckier on 22 September. Early in the morning of that day, a lookout on the bridge of U-9, commanded by Lieutenant Otto Weddigen, spotted a vessel on the horizon. Weddigen ordered the U-boat to submerge immediately, and the submarine went forward to investigate.

At closer range, Weddigen discovered three old Royal Navy armoured cruisers, Aboukir, Cressy, and Hogue. These three vessels were not merely antiquated, but were staffed mostly by reservists, and were so clearly vulnerable that a decision to withdraw them was already filtering up through the bureaucracy of the Admiralty. The order did not come soon enough for the ships. Weddigen sent one torpedo into Aboukir. The captains of Hogue and Cressy assumed Aboukir had struck a mine and came up to assist. U 9 put two torpedoes into Hogue, and then hit Cressy with two more torpedoes as the cruiser tried to flee. The three cruisers sank in less than an hour, killing 1,460 British sailors. Three weeks later, on 15 October, Weddigen also sank the old cruiser Hawke, and the crew of U 9 became national heroes. Each was awarded the Iron Cross Second Class, except for Weddigen, who received the Iron Cross First Class.

The sinkings caused alarm within the British Admiralty, which was increasingly nervous about the security of the Scapa Flow anchorage, and the fleet was sent to ports in Ireland and the west coast of Scotland until adequate defenses were installed at Scapa Flow. This, in a sense, was a more significant victory than sinking a few old cruisers; the world's most powerful fleet had been forced to abandon its home base.

[edit] First attacks on merchant ships

On 20 October SS Glitra became the first British merchant vessel to be sunk in World War I. The Glitra, bound from Grangemouth to Stavanger, Norway, was stopped and searched by U-17, under the command of Kapitänleutnant Johannes Feldkirchener. The operation was performed strictly in accordance with the Prize rules, the crew being ordered into the lifeboats before the Glitra was sunk by having her seacocks opened.

Less than a week later, on 26 October, U-24 became the first submarine to attack an unarmed merchant ship without warning, when she torpedoed the steamship Amiral Ganteaume, with 2,500 Belgian refugees aboard. Although the ship did not sink, and was towed into Boulogne, 40 lives were lost, mainly due to panic. The U-boat's commander, Rudolf Schneider, claimed that he had mistaken her for a troop transport.^[2]

On 30 January 1915 U-20, commanded by Kapitänleutnant Otto Dröscher, torpedoed and sank the steamers Ikaria, Tokomaru, and Oriole without warning, and on 1 February fired a torpedo at, but missed, the hospital ship Asturias, despite her being clearly identifiable as a hospital ship by her white paintwork with green bands and red crosses.^[3]

[edit] Unrestricted submarine warfare

By early 1915, all the combatants had lost the illusion that the war could be won quickly, and began to consider harsher measures in order to gain an advantage.

The British, with their overwhelming sea power, had established a naval blockade of Germany immediately on the outbreak of war in August 1914, and in early November 1914 declared it to be a War Zone, with any ships entering the North Sea doing so at their own risk.^[4] The blockade was unusually restrictive in that even foodstuffs were considered "contraband of war". The Germans regarded this as a blatant attempt to starve the German people into submission and wanted to retaliate in kind, and in fact the severity of the British blockade did not go over well in America, either.

Germany could not possibly deal with British naval strength on an even basis, and the only possible way Germany could impose a blockade on Britain was through the U-boat. The German Chancellor, Theobald von Bethmann Hollweg, felt that such a submarine blockade, based on "shoot without warning", would antagonise the United States and other neutrals. However, he was unable to hold back the pressures for taking such a step.

In response to the British declaration in November 1914 that the entire North Sea was now a War Zone, on 4 February 1915 Admiral Hugo von Pohl, commander of the German High Seas Fleet, published a warning in the Deutscher Reichsanzeiger (Imperial German Gazette):

(1) The waters around Great Britain and Ireland, including the whole of the English Channel, are hereby declared to be a War Zone. From February 18 onwards every enemy merchant vessel encountered in this zone will be destroyed, nor will it always be possible to avert the danger thereby threatened to the crew and passengers.

(2) Neutral vessels also will run a risk in the War Zone, because in view of the hazards of sea warfare and the British authorization of January 31 of the misuse of neutral flags, it may not always be possible to prevent attacks on enemy ships from harming neutral ships.^[5]

In time, this would bring non-European nations (such as Brazil and the United States) into the war.

The German U-boat force was now primarily based at Ostend in Belgium, giving the submarines better access to the sea lanes around England. The Germans made use of this advantage, sending out about 20 U-boats to begin the naval blockade. In January, before the declaration of "unrestricted submarine warfare" as the submarine blockade was called, 43,550 tonnes of shipping had been sunk by U-boats. The number of sinkings then steadily increased, with 168,200 tonnes going down in August. Attacking without warning, German U-Boats sank nearly 100,000 GRT per month, an average of 1.9 ships daily.^[5]

On 10 April 1915 the British steamer Harpalyce, a Belgian relief ship and clearly marked as such, was torpedoed without warning by UB-4 near the North Hinder lightship, just outside the strip of sea declared safe by von Pohl. The ship had been en route for America to collect food for starving Belgians, and its sinking outraged American citizens already unhappy at the death of Leon C. Thrasher, drowned when the SS Falaba was sunk on 28 March 1915 by U-28.^[6]

[edit] RMS Lusitania

On 7 May 1915, the liner RMS Lusitania was torpedoed by U-20, 8 mi (13 km) off the Old Head of Kinsale, Ireland, and sank in just 18 minutes. Of the 1,959 people aboard, 1,198 were killed.

Following the incident, the German government attempted to justify it by stating officially that she had been armed with guns, and had "large quantities of war material in her cargo".^[7] It was also stated that since "she was classed as an auxiliary cruiser" Germany had had a right to destroy her regardless of any passengers aboard, and that the warnings issued by the German Embassy prior to her sailing plus the 18 February note declaring the existence of "war zones" relieved Germany of any responsibility for the deaths of American citizens aboard.^[8] The Lusitania had been fitted with gun mounts as part of an aborted conversion into an Armed Merchant Cruiser (AMC), but the guns themselves had never been fitted, however she was still listed officially as an AMC.^[9] While she had carried an estimated 4,200,000 rounds of rifle cartridges, 1,250 empty shell cases, and 18 cases of non-explosive fuses^[10] as part of her cargo, which were listed in her manifest, the rifle cartridges were not officially classed as ammunition by the Assistant Manager of the Cunard Line.^[11]

Of the 139 US citizens aboard the Lusitania, 128 lost their lives, and there was massive outrage in Britain and America, The Nation calling it "a deed for which a Hun would blush, a Turk be ashamed, and a Barbary pirate apologize"^[12] and the British felt that the Americans had to declare war on Germany. However, US President Woodrow Wilson refused to over-react. He said at Philadelphia on 10 May 1915:

There is such a thing as a man being too proud to fight. There is such a thing as a nation being so right that it does not need to convince others by force that it is right^[12]

The massive loss of life caused by the sinking of Lusitania required a definitive response from the US. When Germany began its submarine campaign against Britain, Wilson had warned that the US would hold the German government strictly accountable for any violations of American rights.

Backed by State Department second-in-command Robert Lansing, Wilson made his position clear in three notes to the German government issued on 13 May, 9 June, and 21 July.

The first note affirmed the right of Americans to travel as passengers on merchant ships and called for the Germans to abandon submarine warfare against commercial vessels, whatever flag they sailed under.

In the second note Wilson rejected the German arguments that the British blockade was illegal, and was a cruel and deadly attack on innocent civilians, and their charge that the Lusitania had been carrying munitions. William Jennings Bryan considered Wilson's second note too provocative and resigned in protest after failing to moderate it, to be replaced by Robert Lansing who later said in his memoirs that following the tragedy, he always had the "conviction that we would ultimately become the ally of Britain".

The third note, of 21 July, issued an ultimatum, to the effect that the US would regard any subsequent sinkings as "deliberately unfriendly". While the American public and leadership were not ready for war, the path to an eventual declaration of war had been set as a result of the sinking of the Lusitania.

[edit] Submarine minelayers

The appearance of new minefields off the East coast of Britain in June 1915 was puzzling to the Royal Navy due to the waters being very busy, and was blamed initially on neutral fishing boats. However, on 2 July the small coaster Cottingham accidentally ran down the small coastal U-boat UC-2 off Great Yarmouth, and when she was salvaged she was found to be a submarine minelayer, fitted with twelve mines in six launching chutes.^[13]

On August 21 UC-5 became the first submarine minelayer to penetrate into the English Channel, laying 12 mines off Boulogne, one of which sank the steamship William Dawson the same day. UC-5 laid 6 more mines off Boulogne and Folkestone on 7 September, one of which sank the cable layer Monarch. Further mines were laid off the southeast coast by UC-1, UC-3, UC-6, and UC-7.

[edit] SS Arabic

On 19 August 1915 U-24 sank the White Star liner SS Arabic, outward bound for America, 50 mi (80 km) south of Kinsale. The Arabic was zigzagging at the time, and the commander of U-24 said that he thought she was trying to ram his submarine. He fired a single torpedo which struck the liner aft, and she sank within 10 minutes, with the loss of 44 passengers and crew, 3 of whom were American. On 22 August President Wilson's press officer issued a statement that the White House staff was speculating on what to do if the Arabic investigation indicated that there had been a deliberate German attack. If true, there was speculation that the US would sever relations with Germany, while if it was untrue, negotiations were possible.

At the same time, US Secretary of State Lansing approved Assistant Secretary Chandler Anderson's suggestion for a meeting with German Ambassador Johann Heinrich von Bernstorff to explain informally that if Germany abandoned submarine warfare, Britain would be the only violator of American neutral rights. Anderson met Bernstorff at the Ritz Carlton Hotel in New York and reported to Lansing that Bernstorff had immediately recognized the advantage of making Britain responsible for illegal acts unless Britain ended its war zone.

Following the Arabic incident, German Chancellor Theobald von Bethmann-Hollweg and Foreign Secretary Gottlieb von Jagow decided to tell the Americans about their secret orders of 1 June and 5 June, which instructed submarine commanders not to torpedo passenger ships without notice and provisions for the safety of passengers and crew, and on 25 August Bethmann-Hollweg informed US Ambassador James W. Gerard about the June orders.

Bethmann-Hollweg and von Jagow also sought the Kaiser's approval to spare all passenger ships from submarine attack. This proposal angered the German admiralty, Alfred von Tirpitz offering to resign his post as Naval Secretary. The Kaiser rejected Tirpitz's offer and supported Bethmann and on 28 August the Chancellor issued new orders to submarine commanders and relayed them to Washington. The new orders stated that until further notice, all passenger ships could only be sunk after warning and the saving of passengers and crews. In his note to Bernstorff, Bethmann instructed him to negotiate as follows^[14]:

1. Offer Hague arbitration for the Lusitania and Arabic incidents
2. Passenger liners to be sunk only after warning and saving of lives, provided they do not flee or resist
3. US to endeavor to reestablish free seas on the basis of the Declaration of London

[edit] Depth charges

The depth charge, or "dropping mine" as it was initially named, was first mooted in 1910, and developed into practicality when the British Royal Navy’s Commander in Chief, Admiral of the Fleet Sir George Callaghan, requested its production in 1914. Design work was carried out by Herbert Taylor at HMS Vernon Torpedo and Mine School in Portsmouth, England, and the first effective depth charge, the "Type D", became available in January 1916.

Anti-submarine vessels initially carried only two depth charges, to be released from a chute at the stern of the ship. The first success was the sinking of U-68 off Kerry, Ireland, on 22 March 1916 by the Q-ship Farnborough. Germany became aware of the depth charge following unsuccessful attacks on U-67 on 15 April 1916, and U-69 on 20 April. UC-19 and UB-29 were the only other submarines sunk by depth charges during 1916.^[15]

[edit] Mediterranean U-boat campaign

The German Navy sent their first submarines to the Mediterranean in response to the Anglo-French Dardanelles campaign, after it became obvious that their Austro-Hungarian allies could do little against it with their small submarine force, which nevertheless was successful in defending the Adriatic. The Mediterranean was an attractive theater of operations to the German Admiralstab; a significant proportion of British imports passed through it, it was critical to French and Italian trade, and submarines would be able to operate effectively in it even in autumn and winter when poor weather hampered Atlantic and North Sea operations. Additionally, there were certain choke points through which shipping had to pass, such as the Suez Canal, Malta, Crete, and Gibraltar. Finally, the Mediterranean offered the advantage that fewer neutral ships would be encountered^[16], such as US or Brazilian vessels, since fewer non European citizens then travelled the waters.

The first U-boats sent, the famous U-21 and the two small coastal boats, UB-7 and UB-8, achieved initial success, U-21 sinking the Royal Navy predreadnought battleships HMS Triumph and HMS Majestic on 25 and 27 May respectively on her way to Constantinople, but ran into severe limitations in the Dardanelles, where swarms of small craft and extensive anti-submarine netting and booms restricted their movements.

By the end of June 1915, the Germans had assembled a further 3 prefabricated Type UB I submarines at Pola, 2 of which were to be transferred to the Austrian Navy. They were also assembling 3 Type UC I minelaying submarines, which were ordered converted into transports to carry small quantities of critical supplies to Turkey. However, the UB submarines were hindered by their short operational range and the Dardanelles currents, and in July U-21, the only U-boat with a decent operating range, was damaged by a mine and forced to remain at Constantinople.

On 21 July the ocean-going submarines U-34 and U-35 were detached from service in the Baltic and sent to Cattaro, the Germans deciding to make use of Austrian bases rather than Constantinople, since there were better supply and repair facilities in the Adriatic and it avoided submarines having to negotiate the dangerous passage through the Dardanelles. In August U-33 and U-39 joined the German Mediterranean Flotilla based at Cattaro, following pleas from the German military attaché in Constantinople, who reported that the Royal Navy's close naval support was inflicting heavy losses on Turkish forces at the Gallipoli beachheads.

The German campaign in the Mediterranean is generally agreed to have properly begun in October 1915, when U-33 and U-39, followed later by U-35, were ordered to attack the approaches to Salonika and Kavalla. That month, 18 ships were sunk, for a total of 63,848 tons. It was decided the same month that further reinforcements were called for, and a further large U-boat, U-38 sailed for Cattaro. Since Germany was not yet at war with Italy, even though Austria was, the German submarines were ordered to refrain from attacking Italian shipping in the eastern Mediterranean where the Italians might expect hostile action only from German submarines. When operating in the west, up to the line of Cape Matapan, the German U-boats flew the Austrian flag, and a sinking without warning policy was adopted, since large merchant ships could be attacked on the suspicion of being transports or auxiliary cruisers.

The German Admiralty also decided that the Type UB II submarine would be ideal for Mediterranean service. Since these were too large to be shipped in sections by rail to Pola like the Type UB I, the materials for their construction and German workers to assemble them were sent instead. This meant a shortage of workers to complete U-boats for service in home waters, but it seemed justified by the successes in the Mediterranean in November, when 44 ships were sunk, for a total of 155,882 tons. The total in December fell to 17 ships (73,741 tons) which was still over half the total tonnage sunk in all theaters of operation at the time.

In November 1915 U-38 caused a diplomatic incident when she sank two Italian steamers while sailing under the Austrian flag, and the loss of 40 American citizens caused the "sinking without warning" policy to be abandoned until the resumption of unrestricted submarine warfare in 1917. A similar "false flag" incident in March 1916 was an influence on Italy's decision to declare war on Germany in August 1916.^[17]

[edit] Resumption of unrestricted submarine warfare

On 22 December 1916, Admiral von Holtzendorff composed a memorandum which became the pivotal document for Germany's resumption of unrestricted U-boat warfare in 1917. Holtzendorff proposed breaking Britain's back by sinking 600,000 tons of shipping per month, based on a February 1916 study by Dr. Richard Fuss, who had postulated that if merchant shipping was sunk at such a rate, Britain would run out of shipping and be forced to sue for peace within 6 months, well before the Americans could act. Even if the "disorganized and undisciplined" Americans did intervene, Holtzendorff assured the Kaiser, "I give your Majesty my word as an officer, that not one American will land on the Continent."^[18]

On 9 January 1917, the Kaiser met with Chancellor Bethmann-Hollweg and military leaders at Schloss Pless to discuss measures to resolve Germany's increasingly grim war situation; its military campaign in France had bogged down, and with Allied divisions outnumbering German ones by 190 to 150, there was a real possibility of a successful Allied offensive. Meanwhile, the German navy was bottled up in its home port of Kiel, and the British blockade had caused a food scarcity that was in turn causing deaths due to malnutrition. The military staff urged the Kaiser to unleash the submarine fleet on shipping travelling to Britain, Hindenburg advising the Kaiser that "The war must be brought to an end by whatever means as soon as possible." The Kaiser duly signed the order for unrestricted submarine warfare to resume on 1 February 1917; the Chancellor, who had opposed the decision, said "Germany is finished".

On 27 January, Admiral Beatty observed that "The real crux lies in whether we blockade the enemy to his knees, or whether he does the same to us."^[19]

Germany had 105 submarines ready for action on 1 February: 46 in the High Seas Fleet; 23 in Flanders; 23 in the Mediterranean; 10 in the Baltic; and 3 at Constantinople. Fresh construction ensured that, despite losses, at least 120 submarines would be available for the rest of 1917. The campaign was initially a great success, nearly 500,000 tons of shipping being sunk in both February and March, and 860,000 tons in April, when Britain's supplies of wheat shrank to 6 weeks worth. In May losses exceeded 600,000 tons, and in June 700,000. Germany had lost only 9 submarines in the first three months of the campaign.^[19]

On 3 February, in response to the new submarine campaign, President Wilson severed all diplomatic relations with Germany, and declared war on 6 April.

[edit] Allied response

The new policy of unrestricted submarine warfare was initially a success; in January Britain lost 49 ships; in February, 105; and in March, 147. A full 25% of all Britain-bound shipping was sunk.

The British Admiralty failed to respond effectively to the German offensive, initially refusing to consider convoying or escorting, which they considered defensive measures, despite the proven success of troop convoys earlier in the war, the Channel convoys between England and France, and the Dutch, French, and Scandinavian convoys in the North Sea. It was not until 27 April that the Admiralty endorsed the convoy system, the first convoy sailing from Gibraltar on 10 May.^[19]

In April, US Rear Admiral William Sims arrived in London as US Naval Liaison. He was dismayed to be informed by the Admiralty that Germany would win the war if its submarines went unchecked, and cabled Washington to have USN destroyers despatched to Queenstown, Ireland, from where they were to patrol to the west.^[19]

As merchantmen from Allied countries were sunk, Brazilian ships took over routes that had been vacated. However, this led the Brazilian vessels into waters patrolled by U-boats. When coupled with Germany's policy of unrestricted submarine warfare, the result was that Brazilian ships were soon lost, which drove the country closer to declaring war on the Central Powers.^[20]

In May and June a regular system of transatlantic convoys were established, and after July the monthly losses never exceeded 500,000 tons, although they remained above 300,000 tons for the remainder of 1917. German submarine losses were between 5 and 10 each month, and they soon realized the need to increase production, even at the expense of building surface warships. However, production was delayed by labour and material shortages.^[19]

[edit] American campaign

Late in the war, the German high command decided to take the submarine war to the coast of the US, using the large Type U-151 U-boats. The Type U-151 carried 18 torpedoes and two 105 mm deck guns, and had a range of around 25,000 nautical miles (46,300 km). Seven had been built in 1916, originally as large merchant U-boats for shipping material to and from locations otherwise denied German surface ships, such as the United States, and 6 were refitted for war duty in 1917. They were the largest U-boats of World War I.

U-151 departed Kiel on 14 April 1918 commanded by Korvettenkapitän Heinrich von Nostitz und Jänckendorff, her mission to attack American shipping. She arrived in Chesapeake Bay on 21 May where she laid mines off the Delaware capes, and cut the submerged telegraph cables which connected New York with Nova Scotia. On 25 May she stopped three US schooners off Virginia, took their crews prisoner, and sank the three ships by gunfire. On 2 June 1918, known to some historians as "Black Sunday", U-151 sank six US ships and damaged two others off the coast of New Jersey in the space of a few hours. The next day the tanker Herbert L. Pratt struck a mine previously laid by U-151 in the area but was later salvaged. Only 13 people died in the seven sinkings, their deaths caused by a capsized lifeboat.^[21] She returned to Kiel on 20 July 1918 after a 94-day cruise in which she had covered a distance of 10,915 mi (17,566 km), sunk 23 ships totalling 61,000 tons, and had laid mines responsible for the sinking of another 4 vessels.^[22]

Encouraged by the success of U-151, U-156, U-117, and the large Type 139 U-cruiser U-140 were despatched on similar missions, but the US Navy was now ready for them, and the hunting was not as good. U-156 was lost with all hands on the return voyage when she struck a mine off Bergen, Norway, on 25 September 1918. Another trio of long-range submarines, U-155, U-152, and U-cruiser U-139 were making their way across the Atlantic in November 1918 when the war ended.

A few of the U-cruisers also made long voyages south to the Azores and the African coast, where they operated generally unmolested against shipping operating in the area, though one, U-154, was torpedoed by the British submarine HMS E35 off the coast of Portugal in May 1918.

[edit] Japanese participation

Beginning in April 1917, Japan, an ally of Great Britain, 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, in contrast to the Italian Navy which was described as "languid and apathetic".^[23] 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).

[edit] Brazilian Participation

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 the 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.^[24]

[edit] The end

By 1918 U-boat losses had reached unacceptable levels, while the morale of their crews had drastically deteriorated and by the autumn it became clear that the Central Powers could not win the war. On 1 October 1918 the large Type U 139 submarine U-139, commanded by Kapitänleutnant Lothar von Arnauld de la Perière, became the last German submarine to sink an enemy vessel in World War I, when Perière torpedoed a vessel belonging to an escorted convoy off Finisterre.

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 to be broken up. The last significant role played by U-boats in WWI 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".^[25]

[edit] Summary

[edit] Allied and Neutral Tonnage sunk by submarines in World War I

Month	1914	1915	1916	1917	1918
January		47,981	81,259	368,521	306,658
February		59,921	117,547	540,006	318,957
March		80,775	167,097	593,841	342,597
April		55,725	191,667	881,027	278,719
May		120,058	129,175	596,629	295,520
June		131,428	108,855	687,507	255,587
July		109,640	118,215	557,988	260,967
August	62,767	185,866	162,744	511,730	283,815
September	98,378	151,884	230,460	351,748	187,881
October	87,917	88,534	353,660	458,558	118,559
November	19,413	153,043	311,508	289,212	17,682
December	44,197	123,141	355,139	399,212
Total	312,672	1,307,996	2,327,326	6,235,878	2,666,942

Grand Total 12,850,814 gross tons

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.^[26]

[edit] German Submarine Force 1914-1918

	1914	1915	1916	1917	1918
On hand	24	29	54	133	142
Gains	10	52	108	87	70
Battle losses	5	19	22	63	69
Other losses		8	7	15	9??
Years end	29	54	133	142	134

• Total operational boats: 351
• Total sunk in combat (50%): 178
• Other losses (11%): 39
• Completed after Armistice: 45
• Surrendered to Allies: 179

[edit] Notes

[edit] References

• Gibson, R.H.; Maurice Prendergast (2002). The German Submarine War 1914-1918. Periscope Publishing Ltd.. ISBN 1904381081. 
• Compton-Hall, Richard (2004). Submarines at War 1914-18. Periscope Publishing Ltd.. ISBN 1557504474. 
• Halpern, Paul G. (1995). A Naval History of World War I. Routledge. ISBN 1857284984. 
• Scheina, Robert L. (2003). Latin America's Wars. Washington D.C.: Brassey's. ISBN 1574884522. http://books.google.com/books?id=8aWQ_7oKJfkC. 

[edit] External links

• World's Navies in World War 1, Campaigns, Battles, Warship losses
• "First Battle of the Atlantic" article.

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