A History of Sea Power Part 32

OCEAN-GOING TYPES FROM ABOUT U 51 to U 70

OCEAN-GOING TYPES FROM U 19 TO U 28

OCEAN-GOING TYPES FROM ABOUT U 30 UP TO U 39

U 151-157 (OCEAN-GOING)

OCEAN-GOING TYPES OF GERMAN SUBMARINES]

_Anti-Submarine Tactics_

Of the general categories of anti-submarine tactics,--detection, evasion, and destruction--it was naturally those of evasion that were first employed. Among these may be included suspension of sailings upon warning of a submarine in the vicinity, diversion of traffic from customary routes, camouflage, and zigzag courses to prevent the enemy from securing favorable position and aim.

The first method was effective only at the expense of a severe reduction of traffic, amounting in the critical months of 1917 to 40 per cent of a total stoppage. The second sometimes actually aided the submarine, for in confined areas such as the Mediterranean it was likely to discover the new route and reap a rich harvest.

Camouflage was discarded as of slight value; but shifts of course were employed to advantage by both merchant and naval vessels throughout the war.

Methods of detection depended on both sight and sound. Efficient lookout systems on shipboard, with men a.s.signed to different sectors so as to cover the entire horizon, made it possible frequently to detect a periscope or torpedo wake in time to change course, bring guns to bear, and escape destruction. According to a British Admiralty estimate, in case a submarine were sighted the chances of escape were seven to three, but otherwise only one to four.

Aircraft of all kinds proved of great value in detecting the presence of U-boats, as well as in attacking them. Hydrophones and other listening devices, though at first more highly perfected by the enemy, were so developed during the war as to enable patrol vessels to discover the presence and even determine the course and speed of a submerged foe. Along with these devices, a system of information was organized which, drawing information from a wide variety of sources, enabled Allied authorities to trace the cruise of a U-boat, antic.i.p.ate its arrival in a given locality, and prophesy the duration of its stay.

Among methods of destruction, the mounting of guns on merchantmen was chiefly valuable, as already suggested, because of its effect in forcing submarines to resort to illegal and barbarous methods of warfare. Hitherto, submarines had been accustomed to operate an the surface, board vessels, and sink them by bombs or gunfire. Visit and search, essential in order to avoid injury to neutrals, was now out of the question, for owing to the surface vulnerability of the submarine it might be sent to the bottom by a single well-directed shot. In brief, the guns on the merchant ship kept submarines beneath the surface, forced them to draw upon their limited and costly supply of torpedoes, and hindered them from securing good position and aim for torpedo attack.

Much depended, of course, upon the range of the ship's guns and the size and experience of the gun-crews. When the United States began arming her ships in March, 1917, she was able to put enough trained men aboard to maintain lookouts and man guns both night and day. A dozen or more exciting duels ensued between ships and U-boats before the latter learned that such encounters did not repay the risks involved. On October 19, 1917, the steamer _J.

L. Luckenbach_ had a four-hour running battle with a submarine in which the ship fired 202 rounds and the pursuer 225. The latter scored nine hits, but was at last driven off by the appearance of a destroyer. To cite another typical engagement, the _Navajo_, in the English Channel, July 4, 1917, was attacked first by torpedo and then by gunfire. The 27th shot from the ship hit the enemy's conning tower and caused two explosions. "Men who were on deck at the guns and had not jumped overboard ran aft. The submarine canted forward at an angle of almost 40 degrees, and the propeller could be plainly seen lashing the air."[1]

[Footnote 1: For more detailed narratives of this and other episodes of the submarine campaign, see Ralph D. Payne, THE FIGHTING FLEETS, 1918.]

In coastal waters where traffic converged, large forces of destroyers and other craft were employed for purposes of escort, mine sweeping, and patrol. Yet, save as a means of keeping the enemy under water and guarding merchant ships, these units had only a limited value owing to the difficulty of making contact with the enemy. During the later stages of the war destroyers depended chiefly upon the depth bomb, an invention of the British navy, which by means of the so-called "Y guns" could be dropped in large numbers around the supposed location of the enemy. It was in this way that the United States Destroyers _Fanning_ and _Nicholson_, while engaged as convoy escorts, sank the _U-58_ and captured its crew.

The "mystery" or "Q" ships (well-armed vessels disguised as harmless merchantmen) were of slight efficacy after submarines gave up surface attack. In fact, it was the submarine itself which, contrary to all pre-war theories, proved the most effective type of naval craft against its own kind. Whereas fuel economy compelled German submarines to spend as much time as possible on the surface, the Allied under-water boats, operating near their bases, could cruise awash or submerged and were thus able to creep up on the enemy and attack unawares.

According to Admiral Sims, Allied destroyers, about 500 in all, were credited with the certain destruction of 34 enemy submarines; yachts, patrol craft, etc., over 3000 altogether, sank 31; whereas about 100 Allied submarines sank probably 20.[1] Since 202 submarines were destroyed, this may be an underestimate of the results accomplished by each type, but it indicates relative efficiency. Submarines kept the enemy beneath the surface, led him to stay farther away from the coast, and also, owing to the disastrous consequences that might ensue from mistaken ident.i.ty, prevented the U-boats from operating in pairs. The chief danger encountered by Allied submarines was from friendly surface vessels. On one occasion an American submarine, the AL-10, approaching a destroyer of the same service, was forced to dive and was then given a bombardment of depth charges. This bent plates, extinguished lights, and brought the submarine again to the surface, where fortunately she was identified in the nick of time. The two commanders had been roommates at Annapolis.

[Footnote 1: THE VICTORY AT SEA, _World's Work_, May, 1920, p. 56.]

_Work of the United States Navy_

Having borne the brunt of the naval war for three years, the British navy welcomed the reenforcements which the United States was able to contribute, and shared to the utmost the experience already gained. On May 3, 1917, the first squadron of 6 American destroyers arrived at Queenstown, and was increased to 50 operating in European waters in November, and 70 at the time of the armistice. A flotilla of yachts, ill adapted as they were for such service, did hazardous duty as escorts in the Bay of Biscay; and a score of submarines crossed the Atlantic during the winter to operate off Ireland and in the Azores. Five dreadnoughts under Admiral Rodman from the U.

S. Atlantic fleet became a part of the Grand Fleet at Scapa Flow.

Probably the most notable work of the American navy was in projects where American manufacturing resources and experience in large-scale undertakings could be brought to bear. In four months, from July to November, 1917, the United States Navy constructed an oil pipe line from the west to the east coast of Scotland, thus eliminating the long and dangerous northern circuit. Five 14-inch naval guns, on railway mountings, with a complete train of 16 cars for each gun, were equipped by the navy, manned entirely with naval personnel, and were in action in France from August, 1918, until the armistice, firing a total of 782 rounds on the German lines of communication, at ranges up to 30 miles.

The American proposal of a mine barrage across the entrance to the North Sea from Scotland to Norway at first met with slight approval abroad, so unprecedented was the problem of laying a mine-field 230 miles in length, from 15 to 30 miles in width, and extending at least 240 feet downward in waters the total depth of which was 400 or more feet. Even the mine barrier at the Straits of Dover had proved ineffective owing to heavy tides, currents, and bad bottom conditions, until it was strengthened by Admiral Keyes in 1918. By employing a large type of mine perfected by the United States Naval Bureau of Ordnance, it was found possible, however, to reduce by one-third the number of mines and the amount of wire needed for the North Sea Barrage. The task was therefore undertaken, and completed in the summer of 1918. Out of a total of 70,000 mines, 56,570, or about 80 per cent, were planted by American vessels. The barrage when completed gave an enemy submarine about one chance in ten of getting through. According to reliable records, it accomplished the destruction or serious injury of 17 German submarines, and by its deterrent effect, must have practically closed the northern exit to both under-water and surface craft.

[Ill.u.s.tration: OSTEND-ZEEBRUGGE AREA]

_The Attack on Zeebrugge and Ostend_

At the Channel exit of the North Sea, a vigorous blow at the German submarine nests on the Belgian coast was finally struck on April 22-23, 1918, by the Dover Force under Vice Admiral Roger Keyes, in one of the most brilliant naval operations of the war. Of the two Belgian ports, Ostend and Zeebrugge, the latter was much more useful to the Germans because better protected, less exposed to batteries on the land front, and connected by a deeper ca.n.a.l with the main base 8 miles distant at Bruges. It was planned, however, to attack both ports, with the specific purpose of sinking 5 obsolete cruisers laden with concrete across the entrances to the ca.n.a.ls. The operation required extensive reconstruction work on the vessels employed, a thorough course of training for personnel, suitable conditions of atmosphere, wind, and tide, and execution of complicated movements in accordance with a time schedule worked out to the minute.

At Ostend the attack failed owing to a sudden shift of wind which blew the smoke screen laid by motor boats back upon the two block ships, and so confused their approach that they were stranded and blown up west of the entrance.

At Zeebrugge, two of the three block ships, the _Iphigenia_ and the _Intrepid_, got past the heavy guns on the mole, through the protective nets, and into the ca.n.a.l, where they were sunk athwart the channel by the explosion of mines laid all along their keels.

To facilitate their entrance, the cruiser _Vindictive_ (Commander Alfred Carpenter), fitted with a false deck and 18 brows or gangways for landing forces, had been brought up 25 minutes earlier--to be exact, at a minute past midnight--along the outer side of the high mole or breakwater enclosing the harbor. Here, in spite of a heavy swell and tide, she was held in position by the ex-ferryboat _Daffodill_, while some 300 or 400 bluejackets and marines swarmed ash.o.r.e under a violent fire from batteries and machine guns and did considerable injury to the works on the mole. Fifteen minutes later, an old British submarine was run into a viaduct connecting the mole with the sh.o.r.e and there blown up, breaking a big gap in the viaduct. Strange to say, the _Vindictive_ and her auxiliaries, after lying more than an hour in this dangerous position, succeeded in taking aboard all survivors from the landing party and getting safely away. Motor launches also rescued the crews of the blockships and the men--all of them wounded--from the submarine. One British destroyer and two motor boats were sunk, and the casualties were 176 killed, 412 wounded, and 49 missing. For a considerable period thereafter, all the larger German torpedo craft remained cooped up at Bruges, and the Zeebrugge blockships still obstructed the channel at the end of the war.

[Ill.u.s.tration: ZEEBRUGGE HARBOR WITH GERMAN DEFENSES AND BRITISH BLOCKSHIPS]

_The Convoy System_

Of all the anti-submarine measures employed, prior to the North Sea Barrage and the Zeebrugge attack, the adoption of the convoy system was undoubtedly the most effective in checking the loss of tonnage at the height of the submarine campaign. Familiar as a means of commerce protection in previous naval wars, the late adoption of the convoy system in the World War occasioned very general surprise. It was felt by naval authorities, however, that great delay would be incurred in a.s.sembling vessels, and in restricting the speed of all ships of a convoy to that of the slowest unit.

Merchant captains believed themselves unequal to the task of keeping station at night in close order, with all lights out and frequent changes of course, and they thought that the resultant injuries would be almost as great as from submarines. Furthermore, so long as a large number of neutral vessels were at sea, it appeared a very doubtful expedient to segregate merchant vessels of belligerent nationality and thus distinguish them as legitimate prey.

[Ill.u.s.tration: BRITISH, ALLIED AND NEUTRAL MERCHANT SHIPS DESTROYED BY GERMAN RAIDERS, SUBMARINES AND MINES

(Figures in thousands of gross tons)

The accompanying chart shows the merchant shipping captured or destroyed by Germany in the course of the war. After 1914 the losses were inflicted almost entirely by submarines, either by mine laying or by torpedoes. According to a British Admiralty statement of Dec. 5, 1919, the total loss during the war was 14,820,000 gross tons, of which 8,918,000 was British, and 5,918,000 was Allied or neutral. The United States lost 354,450 tons. During the same period the world's ship construction amounted to 10,850,000 tons, and enemy shipping captured and eventually put into Allied service totalled 2,393,000 tons, so that the net loss at the close of the war was about 1,600,000 tons.]

But in April, 1917, the situation was indeed desperate. The losses had become so heavy that of every 100 ships leaving England it was estimated that 25 never returned.[1] The American commander in European waters, Admiral Sims, reports Admiral Jellicoe as saying at this time, "They will win unless we can stop these losses--and stop them soon."[2] Definitely adopted in May following, the convoy system was in general operation before the end of the summer, with a notable decline of sinkings in both the Mediterranean and the Atlantic. The following table, based on figures from the Naval Annual for 1919, indicates the number of vessels sunk for each submarine destroyed. It shows the decreased effectiveness of submarine operations after September 1, 1917, which is taken as the date when the convoy system had come into full use, and brings out the crescendo of losses in 1917.

[Footnote 1: Bra.s.sey's NAVAL ANNUAL, 1919.]

[Footnote 2: _World's Work_, Sept., 1919.]

------------------------------------------------------------------------- |Vessels sunk| | | per | Total No. | | submarine | sunk | | destroyed | | --------------|------------|-----------|--------------------------------- Aug. 1, 1914- | 10.4 | |69 ships sunk, almost entirely by Feb., 1915 | | | surface cruisers.

| | | Feb. 1, 1915- | 48 | 544 |Half by torpedo; 148 without Feb. 1, 1917 | |(two years)| warning; 3,066 lives lost.

| | | Feb. 1, 1917- | 67 | 736 |572 by torpedo; 595 (69%) with Sept. 1, 1917 | |(7 months) | out warning.

| | | Sept. 1, 1917-| 20.2 | 548 |448 (82%) without warning.

April 1, 1918 | |(7 months) | | | | April 1, 1918-| 12 | 252 |239 (91%) without warning.

Nov. 1, 1918 | |(7 months) | -------------------------------------------------------------------------

From July 26, 1917, to October 26, 1918, 90,000 vessels were convoyed, with a total loss from the convoys of 436, or less than half of one per cent. The convoy system forced submarines to expose themselves to the attacks of destroyer escorts, or else to work close in sh.o.r.e to set upon vessels after the dispersion of the convoy. But when working close to the coast they were exposed to Allied patrols and submarines.

Testifying before a German investigation committee, Captain Bartenbach, of the V-boat section of the German Admiralty, gave the chief perils encountered by his boats as follows: (1) mines, (2) Allied submarines, which "destroyed a whole series of our boats," (3) aircraft of all types, (4) armed merchantmen, (5) hydrophones and listening devices.

Admiral Capelle in his testimony referred to the weakening of their efforts due to "indifferent material and second-rate crews."

_Transport Work_

Dependent in large measure upon the anti-submarine campaign for its safety and success, yet in itself an immense achievement, the transport of over 2,000,000 American troops to France must be regarded as one of the major naval operations of the war. Of these forces 48% were carried in British, and 43% in American transports. About 83% of the convoy work was under the protection of American naval vessels.

The transportation work of the British navy, covering a longer period, was, of course, on a far greater scale. Speaking in Parliament on October 29, 1917, Premier Lloyd George indicated the extent of this service as follows: "Since the beginning of the war the navy has insured the safe transportation to the British and Allied armies of 13,000,000 men, 12,000,000 horses, 25,000,000 tons of explosives and supplies, and 51,000,000 tons of coal and oil. The loss of men out of the whole 13,000,000 was 3500, of which only 2700 were lost through the action of the enemy. Altogether 130,000,000 tons have been transported by British ships." These figures, covering but three years of the war, are of significance chiefly as indicating the immense transportation problems of the British and Allied navies and the use made of sea communications.

These three main Allied naval operations--the blockade of Germany, the anti-submarine campaign, and the transportation of American troops to France--were unquestionably decisive factors in the war.

Failure in any one of them would have meant victory for Germany. The peace of Europe, it is true, could be achieved only by overcoming Germany's military power on land. A breakdown there, with German domination of the Continent, would have created a situation which it is difficult to envisage, and which very probably would have meant a peace of compromise and humiliation for England and America.

It is obvious, however, that, but for the blockade, Germany could have prolonged the war; but for American reenforcements, France would have been overrun; but for the conquest of the submarine, Great Britain would have been forced to surrender.

In the spring of 1918 Germany ma.s.sed her troops on the western front and began her final effort to break the Allied lines and force a decision. With supreme command for the first time completely centralized under Marshal Foch, and with the support of American armies, the Allies were able to hold up the enemy drives, and on July 18 begin the forward movement which pushed the Germans back upon their frontiers. Yet when the armistice was signed on November 11, the German armies still maintained cohesion, with an unbroken line on foreign soil. Surrender was made inevitable by internal breakdown and revolution, the first open manifestations of which appeared among the sailors of the idle High Seas Fleet at Kiel.

On November 21, 1918, this fleet, designed as the great instrument for conquest of world empire, and in its prime perhaps as efficient a war force as was ever set afloat, steamed silently through two long lines of British and Allied battleships a.s.sembled off the Firth of Forth, and the German flags at the mainmasts went down at sunset for the last time.

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