Introduction
Over 1939-1945, WW2 raged from Britain's declaration of war on the 3rd of September 1939, until the surrender of Japan on the 2nd. of September 1945.

The Submarine menace operating against the enemy's Naval and Merchant shipping was a constant threat. Churchill said: "The only thing that ever frightened me during the war was the U-Boat peril."

In this article I propose to review the operation of the submarine service of the main protagonists ranged against each other in WW2, Germany, Italy and Japan versus Britain, USA and Russia.

Which country controlled the most efficient Submarine Fleet during this global conflict?

But then, how does one measure efficiency in this arena? Is it the greatest tonnage sunk by a specific submarine service?  No, I suggest the only way one can arrive at the most efficient use of a submarine service, is by recording the actual tonnage sunk for each submarine that was destroyed. I propose to set up a table which ranks each country's submarine service by this measure.

Germany
The German U-Boats played a major role in their country's fight for world domination. At the outbreak of war, German boats used an air driven torpedo, similar to the British counterpart, but it was quite unreliable, it exhibited erratic depth keeping qualities, and the magnetic pistol for exploding its warhead also gave problems.

Admiral Donitz, the U-Boat Commander commented thus: "I do not believe that ever in the history of war, have men been sent against the enemy with such a useless weapon." Germany now developed a trackless torpedo fitted with a contact pistol to fire the warhead, this new weapon soon proved its effectiveness.

The U-Boats wreaked havoc on Allied shipping, sinking 14,500,000 tons, across the oceans of the world - out of this total, 11,904,954, tons were sunk in the North Atlantic during the desperately fought Battle of the Atlantic.  This was the one fight in WW2 that had to be won, the rest of the war including landing on the mainland of Europe depended upon victory against the U-Boat menace. Britain could not survive without the food, oil, military hardware and troops that flowed across this wretched stretch of water between North America and Britain.

Dependent on the source of one's statistics, the number of U-Boats sunk or captured during the war will vary, but in general, this figure may be taken to fall between 781 - 785.

Although eventually fitted with the Schnorchel, allowing them to charge their batteries, whilst breathing below the surface, making them even harder to detect, over the 1944 period of June to December, 140 boats did not make it back to base.

U-Boat command paid a huge price in the loss of personnel, of 40,600 officers and men involved, 30,246 died, with another 5,338 were taken as prisoners of war.

There is little doubt that the German U-Boat arm faced the most efficient anti-submarine force operating in WW2, namely the Royal Navy. eg. Captain F J Walker CB, DSO + 3 bars, DSC + 2 bars. Royal Navy, when Commander of the 2nd Escort Group comprising the sloops, Starling, Magpie, Wren, Wildgoose and Woodpecker, destroyed 6 U-Boats over the 31st of January and the 19th. of February, including the capture of U-264, the first German submarine to be fitted with a Schnorchel.

Captain (Johnnie) Walker had the amazing record of 20 U-Boat kills, but, at the age of only 48 he died from a stroke. The total Western Approaches Naval Command mourned his early death, and Admiral Sir Max Horton, at his funeral, held in the cathedral at Liverpool said: "No dust nor weight of stone, but all the waters of the Western Approaches shall be his tomb."

HMS Hesperus bore Walker's body out to sea, where it was consigned to the waters of the North Atlantic Ocean.

Italy
The Italian Navy had about 115 submarines in service when she declared war on Britain in June 1940, although, on the 11th. of March, Mussolini informed Ribbentrop that 120 submarines would be ready in the following May (The Ciano Diplomaaatic Papers 1949.) but then, veracity was not one of Mussolini's strongpoints.

In general, Italy's submarine activities were limited to the Mediterranean, but a limited number of their boats did see service in the Atlantic, Red and Black Seas.

Admiral Donitz was very scathing when commenting on the lack of results from the Italian submarines that operated in the Atlantic.

Some 82 Italian submarines were sunk during their wartime activities, this figure has been cited as 85, but after correspondence I had with the Italian Defence Department in Rome, I have chosen to use the figure of 82.

A further 10 were disarmed, and 6 more put out of action.

It is quite difficult to document the tonnage sunk by Italian submarines, but from the total Warships and Merchant Ship Sinkings at August 1942, I estimate this figure to be about one million tons.

Japan
Japan started the war with 63 operational boats, 48 I Class or large submarines, and 15 of the smaller RO Class, and another 29 submarines were building.

In all, 126 submarines were constructed during the war, and 56 remained at the time of surrender, most of these were inoperable through lack of maintenance or damage sustained at sea.

127 Japanese Submarines (excluding Midgets) were lost in the Pacific War, 70 to ships, 19 to enemy submarines, 18 to aircraft, and the balance from miscellaneous causes.

A number of sources placed the Japanese submarine losses as high as 131, but from correspondence I had with the Japanese Naval Attache in Australia, Captain T Yamamoto, dated  the 9th. of April, 1997, he put this number at 127. 

If I may quote Polmar from his: "Submarines of the Imperial Japanese Navy 1904-1945," the traditional application of Submarines in the Japanese Navy was to operate in Fleet warfare, therefore the Cruiser type Submarines were developed to participate in lengthy Cruise operations, the Fleet type to accompany the Battle Fleet, and the medium size to use in Coastal defence."

Polmar also noted: "So devastating was the anti-submarine warfare, that when the conflict ended, only 9 large attack submarines were still in service."

Japanese submarines accounted for about 184 merchant ships with a tonnage of 907,000 tons, ( included in these figures are 98 US ships of 520,000 tons ).  In addition they sank 2 Aircraft Carriers, 2 Cruisers, and 10 Destroyers.

Hashimoto, in his work: "Sunk. The Story of the Japanese Submarine Fleet. 1942-1945," notes: " The Japanese Submarine Fleet was entirely wiped out, but the Martial spirit of it's Sailors is still with us on the far flung oceans. In the Pacific, the Indian Ocean, and the Atlantic, we remember the multitude of resentful warriors, in our ears we hear the whisper of the VOICES FROM THE BOTTOM OF THE SEA."

The operation of Japan's Submarine Fleet was, in general, disastrous, Crews and Boats were sacrificed through poor planning, and the lack of suitable and efficient
radar.

Britain
The Royal Navy Submarine Service commenced the war with only 18 operational boats in Home waters.

The British lost 75 Submarines, and their underwater Fleet sank 1,500,000 tons of Merchant Shipping, and 169 Warships in all theatres.

The British Merchant Navy had very heavy casualities, losing 30,248 men, whilst the Royal Navy had incredible losses, 73,642 during the war, most of these in the unforgiving North Atlantic. In addition, The Royal Canadian Navy lost more men than did the US Navy, those from Canada paying the ultimate price numbered 1,965 men. To this side of the equation, Coastal Command losses need to be added, another 5,866 airmen, alongside 1,777 Aircraft destroyed.
 
Royal Air Force Coastal Command flew 120,000 sorties, taking 850,000 hours, whilst flying some 100 Million miles.

Referring to the Battle of the Atlantic, Captain S W Roskill, DSC, RN, in his "War at Sea," had this to say: " In all the long history of sea warfare there has been no parallel to this battle, whose field was thousands of square miles of ocean, and to which no limits of time or space could be set."

United States of America
After Pearl Harbor on December the 8th.1941, the US Submarine Fleet numbered 51 Boats (29 at Manila and 22 at Pearl Harbor) with another 73 under construction.

The Japanese Merchant Fleet was decimated by Submarines, (British and Dutch Submarines in the Pacific accounted for 29 ships of 65,000 tons and 10 ships of 42,000 tons respectively).

Although the US Submarine arm claimed 10 million tons of Japanese sunk, made up of 4,000 vessels - post war estimates were just over half of the claimed tonnage sunk, and ship numbers were closer to 33% of those claimed.

United States Submarine Torpedoes
At the start of the war with Japan, the US. steam driven Torpedo was running at a greater depth than that set, up to 10 feet deeper, and the magnetic pistol just did not operate beneath the keels of their target ships. The contact detonator also was defective, and Torpedoes exploded when hitting their targets at much less angles than the ninety degree angle which should be the perfect shot.

The Bureau of Ordinance in the US. responsible for Torpedoes just pig headedly refused to accept that this weapon that they issued to their Submarines could in any way be defective.

Lieutenant J.W.Coe of USS Skipjack  wrote in June 1942, after a patrol on which he had managed to sink four ships: "To make round trips of 8,500 miles into enemy waters, to gain attack position undetected within 800 yards of enemy ships, only to find that the Torpedoes run deep and over half the time fail to explode, seems to me to be an undesirable manner of gaining information which might be determined any morning within a few miles of a Torpedo station in the presence of few hazards."

On the 24th. of July 1943, the Captain of the US. Submarine Tinosa, attacked Tonan Maru 111, a 19,000 ton Whaling Factory.  Commander Daspit now conducted his own tests on the efficacy of US. Torpedoes. He fired four Torpedoes and believed that two hit their target, but this ship did not appear to be damaged, he now fired two more, both hit and the ship stopped, but did not sink. At close range, and at right angles to the target, he loosed off nine Torpedoes, all hit but not one exploded, Daspit now took his last Torpedo home. At long last the Bureau now admitted the Skippers were right and their Torpedoes were defective.

Tests showed that defects in the firing pistol and in the depth keeping qualities were present, these problems were now cured. It had taken almost two years to react to these long reported problems of Submarine Captains that their Torpedoes were hitting targets and were not exploding, and were running too deep.

The American Submarine service enjoyed the greatest success of all Submarines operated by either Allied or Enemy Navies, they sank about five times the tonnage that Japanese Submarines achieved. In all, they lost 52 Boats (two of these in the Atlantic  the least number sunk in any Navy involved in WW2.

However it would be remiss of me if I did not point out that US Submarines operating against Japanese Merchant ships and Navy were pitted against the most inefficient Anti-Submarine force that faced the Allies. By contrast, as already noted, the German U-Boat force were up against the most efficient and determined Anti-Submarine force afloat.

The American Submarine Operational History concedes: "It would do well for all Submariners to humbly ponder the fact that Japanese Anti-Submarine defences were not the best. If our Submarines had been confronted with Allied Anti-Submarine measures, the casuality list of the Submarine force would have been much larger, and the accomplishment of Allied Submarines less impressive."

Initially US. Submarine Skippers were all Annapolis graduates, but the quality of enlisted personnel serving in Submarines was so high - that nearly 50% of them became officers by war's end.  However, many US. Submarine Captains did not stand up to the rigors of war time command that was demanded of them, in 1942, 30% were removed for lack of fitness or lack of results, and 14% for the same reason both in 1943, and 1944.

Although the US Submarine service made up but 2% of the United States Navy, it accounted for 55% of Japanese maritime losses. But, this service paid a high price, out of a total of 16,000 Submariners, 375 Officers, and 3,131 enlisted men died at sea, that was a 22% casuality rating, the highest percentage of all US. armed forces.

It must be said, that American Submarines in the Pacific, with but limited help of a few British and Dutch Boats, played a major role in the defeat of Japan. They decimated that country's Merchant Fleet, choking off essential supplies and preventing people continuing their support of the Japanese war effort.

Russia
Russia commenced the war with 218 Submarines, added another 54, but lost a total of 109 Boats.  Like Japan, Russian Submarines had but limited success, and in the case of the Russian Submarines their kills were in no way commensurate with the loss of 109 Boats. They sank only 160 ships, many of them small, to total  402,437 tons, and their operation was restricted to the Baltic and Black Sea areas. 

However, the largest loss of life accreditated to any one Submarine attack goes to a Soviet Submarine, their S13.
It was on the 30th. of January 1945, that the German Wilhelm Gustloff, of 25,484 tons, was being used as a refugee transport evacuating German troops trying to escape from the Red advance. (between the 23rd. of January and the 8th. of May, 1945, liners carried over 2 million troops from the Baltic to West German ports.)

Wilhelm Gustloff had up to 9000/ 10,000 people jammed on board, this cargo included troops, wounded, nurses, and some civilians, her company at that time over four times her normal peacetime capacity. The Soviet Submarine sighted this ship, lined her up, and fired, three Torpedoes struck home, only 1,000 survived, leaving the approximate number who died some where close to 8,000 or 9,000. These awful figures equate with the loss in the sinking of Lusitana, multiplied some six or seven fold, this single action is noted for the greatest loss of life in Maritime History. 

Results  Achieved by Submarine Fleets versus their losses in World War 2