Forty years ago, at a time when the airplane was an underpowered box kite of short range and meager load-carrying capacity, the German Navy possessed a force of long-range aircraft which were flying scouting missions of up to 24 hours’ duration over the North Sea and carrying out strategic bombing attacks on Great Britain with bomb loads of nearly five tons!
The aircraft concerned were, of course, the Zeppelin rigid airships. They had one fatal weakness—their lifting gas was dangerously inflammable hydrogen. Taking advantage of this, Allied aircraft by the end of the war had practically driven them from the skies, in spite of desperate efforts by the Germans to improve the Zeppelin’s high altitude performance. The history of the rigid airship probably came to an end with the destruction of the Hindenburg in 1937; but the story of their performance as a military weapon in World War I is still a romantic page in aviation history.
Count Zeppelin had built his first rigid airship in 1900 with the thought that it would serve the Fatherland as an ideal long- range air scout, but it was twelve years before the German Navy showed any interest in his invention. This delay was partly a consequence of the numerous accidents to his early ships and partly attributable to the policy of Grand Admiral Tirpitz in building up the German Navy. The German fleet was designed primarily as a political threat against England. What money was available was spent on offensive weapons— battleships and torpedo boats. Such defensive craft as scouting airships found no place in the naval budget. Only under pressure from civilian enthusiasts did the Navy buy its first Zeppelin in 1912. This ship, L1, trained personnel and made a few scouting flights in fleet maneuvers. Early in 1913 a larger ship was laid down. In the fall of that year, however, the L1 was lost in a storm off Heligoland with most of her crew, and a month later on a trial flight the new L2 burned with all hands. There were many demands, both from inside and outside the Navy, to discontinue the airship experiment. Instead, a new ship was ordered, three new crews were assigned to training, and the Admiralty ordered Korvettenkapitän Peter Strasser to duty as the new Commander of the Naval Airship Service. Another man might have taken the assignment as a punishment: to Strasser, a person of tireless energy with an unshakeable faith in the capabilities of the airship and a rare personal charm that made his men worship him, this was an opportunity and a challenge. His determination to exploit the airship to the utmost as a raiding and scouting weapon goes far to explain its great development during the war years. With Strasser’s death in the last raid of the war, the service he had built almost literally fell to pieces.
The outbreak of war in August, 1914, found the Naval Airship Service comparatively ignored, with one ship, the Zeppelin L3, and not even a base of its own. Suddenly everything changed. The High Seas Fleet, with no offensive plans and a pessimistic conviction of its own inferiority to the British Navy, had at once to improvise a scouting system to give warning of the expected British operations. Great faith was suddenly placed in the Zeppelin, and more ships were ordered. In addition to the main base already under construction at Nordholz, outlying bases were started at Hage near the Dutch frontier and at Tondern near the Danish border. The Zeppelin was on its way to its greatest period of development— sixty-one in all were to serve in the German Navy during the war.
All the Zeppelins had a number of features in common. A rigid framework of duralumin girder longitudinals and wire-braced transverse rings was covered with clear doped cotton fabric and contained between fourteen and nineteen separate gas cells. These were made gas tight by gluing gold beaters’ skin—the intestinal lining of cattle—onto light cotton fabric. Bombs, gasoline, and water ballast were distributed along a keel which ran the length of the ship. Personnel and engines were carried in at first open, and later enclosed and carefully streamlined, gondolas hung below the hull. A varying number of machine guns were carried in the gondolas and on a large top platform near the bow. As far as can be determined from the records, only once were they used successfully against airplanes—on a night in 1918 the L62’s gunners wounded the pilot of an attacking British plane over the Midlands and forced him to land. The ships ascended through dropping water ballast and descended through valving gas. Hydrogen was considered cheap, and a ship would take off with full gas cells even though a high altitude flight was planned, and half the hydrogen in the ship might be blown off as she rose, with release of ballast, to 18,000 feet or more. Some excess load could be carried in the air by dynamic lift, but the ships never took off “heavy.”
The airship bases were large scale engineering projects. The Germans seem never to have thought of the advantages of the mooring mast. They invariably kept their airships in large sheds, when not in use, and manhandled them in and out with ground parties of several hundred men. Although weather conditions might not prohibit flying, the ships were frequently held in their sheds on crucial occasions by cross winds, and a breeze of twelve m.p.h. across the axis of the shed was considered prohibitive. One ingenious solution to this problem was the construction at the Nordholz base of a revolving double shed, 650 feet long, which could be rotated in sixty minutes or less to match the wind direction. Limitations of shed length and height were a real obstacle to progress in airship design. When the first big Zeppelins of the L30 type were coming forward in the summer of 1916, only one double hangar at Nordholz was large enough to accommodate them. That same year, however, a large inland base at Ahlhorn came into service. This station ultimately was to have six double sheds with a capacity of twelve ships, the last hangars built being 850 feet long—longer than the “big barn” at Lakehurst, New Jersey.
The Zeppelins operated throughout the war in the face of a host of difficulties. First was the problem of the highly inflammable hydrogen. One of the service’s worst disasters was the fire and explosion that destroyed the Ahlhorn base on January 5, 1918. The L51 in Shed 1 took fire accidentally; her shed mate, L47, inevitably burned also; L58 in the adjacent Shed 2 exploded, and within a minute, L46 in Shed 3, and the Schütte-Lanz S.L.20 in Shed 4 exploded with tremendous violence, although the two pairs of sheds were separated by a distance of half a mile. Three ships were destroyed in their sheds by fires during inflation, and three Zeppelins and one Schütte-Lanz burned accidentally in the air with all hands. The L10 of the latter group was undoubtedly lost through valving hydrogen in a thunderstorm. Curiously enough it was found possible to fly safely through thunderstorms if the commander was careful not to valve gas, or rise above the “pressure height” where diminished atmospheric pressure would cause the gas to blow off through the automatic valves. On many occasions ships came home after being struck by lightning, the electrical charge being absorbed by the metal framework and running out the tail. Rain and ice could increase the load by several tons, and sometimes a great deal of gas would be lost when ice was thrown off the propellers into the gas cells. Cold air temperatures or high barometric pressure would increase the lift, as would the sun’s heat through expanding the gas.
Weather was always a problem. In the North Sea storms moved from west to east, and British data were unavailable. The ships would frequently set out for England with little idea of the weather they would meet and often would have to turn back on encountering strong winds or heavy rain. Even if the weather were passable, Strasser had to consider the possibility that unfavorable winds the next day might prevent the ships from entering their sheds. Sometimes fog at the bases would keep the ships in the air for an additional twelve to twenty-four hours. While “blind flying” at slow speed in an airship is comparatively easy, at least two ships were lost by being flown into the ground in fog.
The navigation problem was never solved, and gross errors in dead reckoning were the chief reason that the Zeppelins were only rarely able to find their objectives in the English raids. Air speeds averaging only 40-50 m.p.h., together with high winds at higher altitudes, caused large drift errors that were hard to recognize, particularly at night. Occasionally a commander would take star sights if circumstances were favorable, apparently using an ordinary marine sextant from the top gun platform. A few commanders early in the war showed uncanny ability to find their way over England at night from the terrain, but for most of them one river or headland looked very like another. Later, when altitudes of 16,000- 20,000 feet were the rule, the ground was usually obscured by clouds under the ships. In the summer of 1915 the ships began using radio bearings, though these were rarely accurate to within 50 miles, partly because the direction-finding stations were close together on the German coast. Radio bearings were increasingly relied on as the war progressed, but for several years the Zeppelin had to send out signals for the shore stations to take bearings on. The British also were able to locate the ships by their signals and deciphered their messages. At times, with six to ten ships out, wireless discipline would break down completely as the ships competed for bearings. Only in 1918 was it possible for the Zeppelin itself to take bearings on ground stations in the modern manner.
At war’s end the Naval Airship Service included roughly 6000 officers and men. Over fifty crews consisting each of two officers, two warrant officers, and about sixteen men were trained during the war by Dr. Eckener and experts of the Zeppelin Company. Forty officers and 396 other flight crew members were killed during flight operations. The commanders who entered the service early in the war were of high quality, and such men as Mathy, Breithaupt, Peterson, Bocker, and Hirsch showed great determination in accomplishing their missions and unusual skill in airship handling. Later, as the U-boat war took the best of the younger officers, the airship service had to be content with older men.
Scouting for the High Seas Fleet was always the primary mission of the naval Zeppelins, which partly explains the sporadic occurrence of the more spectacular raids on England. The commanders of the Fleet, particularly Scheer, had great faith in airship scouting—perhaps unjustifiably considering the degree to which the Zeppelins were handicapped by bad weather. Throughout the war Strasser aimed to have at least two, and if possible three, ships out before dawn every day on routine twenty-hour searches proceeding west, north-west, and north from Heligoland to look for enemy surface vessels, submarines, or mines. In month of good weather, such as July, 1916, such flights might be made on as many as twenty days; in November, 1915, there was not a single day on which a Zeppelin went out on a “war flight” of any description; usually the weather permitted scouting on five to twelve days per month. Special missions were flown at the request of the Fleet Command, and when possible a ship was sent out the day before a fleet movement to scout along the proposed route. In the several short excursions made by the High Seas Fleet in 1915, the three to five air ships that were ordered out were kept almost within visual range of the fleet flagship, and no attempt was made to cover the North Sea with long range searches.
The German plan for the Battle of Jutland was determined, in a negative way, by the Naval Airship Service. Admiral Scheer originally intended a bombardment of Sunderland for about May 23, 1916, expecting that British forces might be drawn out to be attacked in detail. He counted heavily on his airships to warn him of approaching British forces, and U-boats were stationed off the British coast. Scheer could not take the grave risk of advancing deep into British waters with an inferior fleet unless he could have advance warning of enemy movements, and as day after day passed with weather too bad for airship scouting, he finally elected the lesser risk of an advance north along the Jutland coast. The resulting battle on May 31 was in effect a series of surprise encounters of the type he feared. Five Zeppelins were able to take to the air a few hours before the battle but were unable to sight either friendly or hostile forces because of thick weather. An additional five ships were out early on the morning of June 1. One, the L11, actually sighted part of the Grand Fleet while the High Seas Fleet was on its way home, but her report did not influence Scheer’s movements.
Of greater interest, airshipwise, was the so-called Sunderland operation of August 19, 1916. Here Scheer was carrying out the original plan of four months earlier, and on the day of his thrust towards Sunderland, eight Zeppelins were out, for the first and last time on coordinated strategic scouting missions in connection with a major fleet operation. Four of the Zeppelins made a futile day-long patrol between Scotland and Norway. They were expected to report the southward advance of the Grand Fleet from Scapa Flow, but they arrived over twelve hours after the British force, alerted by wireless intelligence, had passed their scouting line headed south. Some of the other Zeppelins, hampered by low clouds, sporadically sighted the Grand Fleet. The L13 in the south had several contacts with light cruisers and destroyers of the Harwich Force. Scheer did not succeed in getting a clear picture of the enemy movements from either airship or submarine reports, and when the L13 mistakenly reported capital ships to the south, he turned on a futile chase after the Harwich Force—a move which at least carried him out of reach of the superior strength of the Grand Fleet. Scheer later complained that there were not enough Zeppelins to cover the whole North Sea adequately, and Strasser regretted that he had held four ships in reserve for a possible second day’s operations. Admittedly, the Zeppelin commanders as well as their chief showed a lack of experience and training in cooperation with the fleet. But it must be remembered that there had been few fleet sorties until Scheer assumed command in January, 1916; there had been little opportunity to practice fleet exercises, and previous doctrine had tied the scouting airships to the fleet on tactical missions.
There were very few fleet operations after the Sunderland expedition. The routine reconnaissances continued, but their value decreased after the summer of 1917 when the British found it possible to send long-range flying boats into the German side of the North Sea. Two Zeppelins were shot down before the use of this “secret weapon” was discovered, and while reconnaissances were continued at high altitudes, the airships could see much less. Because of the strain on the crews at 15,000 feet or more, each routine scouting flight became as exhausting as a raid on England. The final British countermeasure against the scouting Zeppelins came on August 11, 1918, when the L53 was set afire at 19,000 feet off the German coast by a high performance Sopwith “Camel” flown from a lighter.
It might appear that the British should have dealt with the Zeppelins in their sheds. Actually the Royal Navy made repeated efforts, beginning as early as October 25, 1914, to bomb the airship bases. Small seaplane carriers would be escorted close to the German coast, and a handful of seaplanes would be bombed up, swung out, and flown off the water if possible. Such an attack by seven seaplanes caused great excitement on the German coast on Christmas Day, 1914; one seaplane found the Nordholz base but its bombs did no damage. The seaplane formula never worked, and success came only in the last year of the war when high performance land planes were taken to sea in the pioneer aircraft carrier Furious. On July 19, 1918, seven “Camel” fighters flown off this ship bombed the Tondern hangars, destroying both Zeppelins stationed there, in the first carrier strike in history against a land-based target.
The raids on England were strictly secondary to the scouting missions and possible only in good weather. After one or two early experiments, they were limited to the moonless half of the month. Often the raids were suspended for long periods while improvements were made in the ships’ performance. Actually, throughout the war, the naval Zeppelins made 159 sorties in forty raids against England, dropping a total of 220 tons of bombs on land, which killed 557 people and wounded 1,358. The total monetary loss was slightly over S7,500,000. About 28 tons of bombs fell in London, where 183 died and 516 were injured. A remarkable feature, considering the meager results, was the extreme emotional reaction to the raids on both sides of the North Sea. The airship commanders themselves often returned with incredibly detailed accounts of heavy munitions explosions, large fires, and collapse of whole blocks of buildings when they had dumped their bombs on tiny villages miles from any large city. A combination of faulty navigation, poor visibility, a well-enforced blackout, and wishful thinking contributed to these repeated fantasies. The German public particularly wished to believe, and did believe, that large portions of London and other cities had been laid waste by the Zeppelin raiders. Exaggerated reports were fed in official handouts to the German press, along with mislabeled photographs such as one of the offices of the National Penny Bank, actually damaged in a Zeppelin raid, which was described as “The Ruins of the Bank of England.”
British nervousness over Zeppelin raids went back at least to 1912, when insistent reports of phantom airships over their East Coast towns were made in circumstances resembling the “flying saucer” craze of our own day. When the Zeppelins at last appeared, the British again were overly impressed, partly because of the novelty of attack from the air, partly because a heavy- handed censorship withheld practically all information and made it appear that more damage had been suffered than could be admitted.
The Zeppelin raiders were most successful in the first eighteen months of the war, when the British defenses were virtually nonexistent. The L3 and L4 made the first attack on January 19, 1915, dropping about half a ton of bombs each on small East coast ports. The next raid was not made until April, and a few scattered attacks were made, usually by single ships, in the spring and early summer. The redoubtable Mathy, then commanding L9, and Hirsch in the L10 did $400,000 damage between them in attacks on Hull and Tyneside. “Squadron raids” with up to five of the standardized L10-type of Zeppelin were begun in August, with London the prime objective. On September 8, 1915, Mathy in the L13 reached the heart of London, dropped nearly two tons of bombs including the first 660- pounder carried to England, and started fires in the City that did S2,700,000 worth of damage. This was the most destructive raid of the war. On October 13 five Zeppelins set out for London, three reached it, and Breithaupt in the L15 did 8250,000 damage in the heart of the capital. The Germans, preoccupied with winning the war by destroying London, had neglected other cities, but on January 31, 1916, a big effort was made against the Midlands by nine ships under orders to bomb Liverpool. Hampered by foul weather, they badly damaged several smaller cities which were keeping a bad blackout, but they could not find the west coast seaport though four claimed to have done so.
Up to this time the Zeppelins had sustained few losses—one raider brought down by gunfire, a few others damaged—and the primitive airplanes used by the defenders had been unable even to come close to the airships. Both Mathy and Peterson, interviewed by American reporters, expressed contempt for the British flying corps. But following the January raid on the Midlands, public agitation forced an extensive reorganization of the defenses. More effort was put into night flying, and in the summer of 1916 the British planes were at last armed with incendiary and explosive machine gun ammunition.
These changes did not bring immediate results. In the spring and summer of 1916 there were a whole series of raids—once there was an attack every night for a week—but results were minor, and London was not bombed. Then, on August 24, 1916, Mathy in the L31, one of the big “super-Zeppelins,” reached London. Showing his customary skill and decision, he dropped over three tons of bombs in a swift five-minute attack that did 8650,000 worth of damage and was away before the defenses could reply. His report inspired Strasser to send out twelve ships against the capital on September 2, and the Army airship service, in a rare moment of cooperation, agreed to add four more. Against this armada, the largest ever dispatched against England, the night flying airplanes at last were to have a success. The Army Schütte-Lanz SL11, one of the first across the coast, was caught at 12,000 feet over the northern suburbs of London and set afire. The awesome spectacle took the heart out of the other commanders; their track charts show their turning back and dumping their bombs as they made for home. Although seventeen tons of bombs were dropped, there were only four deaths and about 8100,000 damage.
Strasser believed that the big 2,000,000 cubic foot ships could evade the airplanes over London, and in the next raid, on September 23, a squadron of three of them made for the capital across Belgium, while the older ships were ordered to the Midlands. Mathy, using magnesium flares to blind the ground defenses, dropped nearly five tons of bombs while crossing the city from south to north, and got away. Bocker, whose L33 had been commissioned only three weeks before, was forced by gunfire damage to land his ship in England. Peterson’s L32 was caught by a plane at 12,000 feet and shot down in flames. Strasser thereafter ordered that London was not to be attacked in clear weather, but on October 1 Mathy met a flaming death at the hands of an airplane defending the capital. His loss profoundly affected the service: the enlisted men who wrote of their experiences agree that the personnel were demoralized for a time, and no commander thereafter flew intentionally over London. In the final raid of the year, on November 27, 1916, two more Zeppelins were destroyed by planes although they restricted themselves to the Midlands.
Even the Kaiser thought then that the raids should be stopped, but Strasser pleaded to be allowed to continue with his ships modified to reach high altitudes. His commanders supported him, and Scheer, who greatly admired Strasser, pointed out that the raids tied up considerable forces in England which otherwise would be employed against the Germans on the Western Front. (At the end [of 1916 over 17,000 men and 110 airplanes were kept in England on home defense.) It was accordingly agreed to continue raiding the Midlands with airships, while large bombing planes were to be produced for raids on London.
In February, 1917, the Navy commissioned the L42, identical in hull structure with the standard “thirties,” but extensively modified for high altitude performance. The “thirties” already in service were similarly altered, and later “height climbers,” as the British called these ships, were further lightened though the hull remained architecturally similar. With these ships the service made a few raids in the spring and summer of 1917, maintaining 16-20,000 foot altitudes over England and having little trouble with enemy planes. The high altitude brought new problems. Engines lost as much as a third of their power, giving the Zeppelins a speed of about 40 m.p.h., while winds at such heights often reached the same velocity. Men were frequently incapacitated by “altitude sickness,” the effect of prolonged cold as low as 36 below zero F. combined with oxygen starvation. Their hardships were intensified because the ships now flew with reduced crews, to save weight, and there was no rest or relief on journeys lasting as long as 24 hours. Frostbite was common. Compressed oxygen, and later liquid air, was available for altitudes over 12,000 feet, but its use was not mandatory. Antifreeze had to be added to ballast water and radiators, but a breakdown often meant a freeze-up so that the engine could not be restarted.
On May 23, 1917, the L44 with Strasser aboard suffered failure of all five engines over England. She made part of the journey home on one engine, and never had more than three in operation. In a small raid on June 16, the L48 was caught by a plane over England at dawn and set afire at 14,000 feet. She had been betrayed by a frozen magnetic compass, which had taken her north when she believed herself to be headed east on a course for home. Her executive officer, in the control car, and a mechanic up in the hull survived her flaming fall—the only such instances on record. The loss of this ship depressed the enlisted men of the service, who had been led to believe that the new Zeppelins would be immune to airplane attack.
The last big raid of the war, on October 19, 1917, was an appalling disaster. Eleven Zeppelins set out, all reached England, but on going up to their attack altitude they found a ferocious gale blowing from the north. Only one ship got home by the usual route across the North Sea. Two returned over Holland. Eight were blown into France. Four of these crossed the trenches and reached Germany. One of these, the L55, inadvertently set an all time airship altitude record of 24,000 feet when her control car personnel lost consciousness while crossing the lines. The others never returned. One was set afire by antiaircraft guns near the Front. Three more, unable to make headway against the wind with engines out of action, and uncertain of their positions, landed in France during the day. One of these ships, the L49, was captured practically intact and formed the basis for the design of the Shenandoah.
Five more ships were lost in the Ahlhorn explosion three months later, and in the last year of the war the attenuated service made only four raids. One attack, on April 12, 1918, gave the British a scare: five Zeppelins were out, each carrying three tons of bombs at altitudes up to 20,000 feet, and the L61 flew boldly across England to within ten miles of the seaport of Liverpool, which had never been attacked throughout the war. At the last minute her commander turned aside to bomb lights at Wigan, which he mistook for Sheffield, and the raid was a failure.
Lack of power at high altitudes was a major cause of the heavy losses in the October 1917 raid. The L70, the last design evolved during the war, was intended to weather such conditions and her seven Maybach “altitude motors” gave her a speed of 82 m.p.h. on her trials in July, 1918. With this proud new giant, Strasser, on August 5, 1918, led four older Zeppelins in a raid on the Midlands. This time the British had high performance aircraft out at sea to meet them; the L70 in the lead was shot down in flames by a DH4, and another ship was attacked by the same plane and barely escaped. In this raid, the last of the war, no bombs were dropped on land. Strasser’s death completely demoralized the entire service. Several of the senior commanders asked to be returned to the Fleet, and in the final months of the war the Zeppelins were hardly out of their sheds. Only seven “front ships” and three training craft were in commission at the Armistice.
Mention should be made of the record flight of the L59 from a base in Bulgaria to Africa in November, 1917. The ship, a standard Navy Zeppelin with a Navy crew, was enlarged to carry fifteen tons of supplies to German troops cut off in East Africa. The airship was recalled over Khartoum, but on landing had hung up a record of 95 hours in the air, 4,200 miles traveled, and had enough fuel for 64 more hours of flight. This feat undoubtedly inspired the postwar intercontinental exploits of the Graf Zeppelin and Hindenburg.
Such was the history of the Zeppelin airships in the German Navy. The modern reader may be surprised at the lack of consistent planning or doctrine in their mushroom development and employment. Yet the same observation could be made about many other new weapons in World War I. At the time the Zeppelins were built, aerial warfare was an unknown quantity, anticipated with exaggerated fears, hopes, and misconceptions. Perhaps little was accomplished by the German Naval Airship Service; but the handicaps were formidable. That so much was done might be considered a tribute to the bravery of its personnel, and above all to the qualities of Peter Strasser, who undoubtedly was one of the outstanding type commanders on either side in World War I.