At the outbreak of the First World War, the German forces had five military Zeppelin1 airships. These were to be used as the first strategic bombers. The Imperial German Navy operated these Luftschiffe (airships) and it was the Navy that brought the War to the British Mainland. A development, the Schütte-Lanz, was used by the Army from 1916.
The Zeppelin is an aircraft which, like a balloon, is filled with a gas lighter than air. In 1914, this was hydrogen, a flammable gas, which, when mixed with the oxygen in the air, is highly explosive. A balloon is a flexible envelope filled with gas, but the Zeppelin had a rigid aluminium framework2 which contained 17 'cells' filled with hydrogen. Engines with propellers were attached to the frame to drive it forwards and control surfaces gave an element of control. The name for this type of structure is dirigible , which means 'steerable'. It was a proven technology, which was almost impossible to bring down by aerial means - it flew so high that aeroplanes could not reach it. Just in case anyone tried, it was armed with five machine guns, some on top of the envelope. Its real sting lay in the bomb load, up to 2000kg (4400lb). It was vulnerable only to the weather and accurate anti-aircraft fire, which was rare in 1914. However, its low air speed of 50mph would prove an Achilles heel as aeroplanes developed.
The Start of the Campaign
These airships were used on all fronts during the First World War with varying success, but their strategic role would be in the bombing of England. Luckily, the greatest exponents of anti-Zeppelin warfare were the British. Initially, the German Emperor - Kaiser Wilhelm II - forbade the use of them against England as it was a 'Christian nation' and considered the bombing of civilians ungentlemanly (the Royal Family were his relations, after all). Due to the stalemate on the Western Front, the military pressured him to start a bombing campaign against the Allies, and he eventually allowed the bombing of England which began in January 1915.
The British answer to this threat was thought out in 1913. Winston Churchill, then State Secretary of the Admiralty, argued the case for the use of aircraft as 'a swarm of hornets' to deter the attacks of these aerial naval ships. He also prompted the start of research into ammunition to defeat them. With the night attack on King's Lynn and Great Yarmouth on 15 January 1915, the race to develop a counter to the Zeppelin began in earnest.
Those pilots whose aircraft managed to reach the height of the Zeppelins soon realised that conventional machine gun ammunition was useless against such a large target. Anti-aircraft guns were equally useless as they could not be directed accurately at the airships in the dark. Searchlights were used to illuminate them, but they only added to the terror of this first aerial bombing of the British mainland3. Thanks to the Kaiser, London was safe until he gave way under more pressure from the military and London Docks were hit on 31 May, 1915. Something had to be done.
To counter the threat, the British developed an elaborate air defence system consisting of a network of anti-aircraft guns, searchlights, fighter aircraft, and a centralised command, control, and intelligence system. The weakest part was the fighter aircraft, which seemed unable to harm the massive Zeppelins.
On the night of 6/7 June, 1915, there was a major breakthrough in the war against the Zeppelin, Sub-Lieutenant RAJ Warneford RN of No 1 Squadron RNAS was off to bomb the Zeppelin sheds at Evere and Berchem-Ste Agathe in a Morane-Saulnier Type L parasol-wing monoplane. He saw a returning Zeppelin (LZ.37) and investigated, only to be driven off by machine gun fire. He followed and waited until it descended to land, then hand-dropped six 20lb Cooper fragmentation bombs on it. Only the last one reached its target, but caused the craft to burst into flames, falling near Ghent. He was awarded the Victoria Cross for this victory.
Other anti-Zeppelin weapons were many and devious. Woolwich Arsenal developed an incendiary round of .45" calibre, fired from old single-shot Martini-Henry cavalry carbines. This calibre was the only available one that could carry an effective payload. There was a particular school of thought that advocated air-to-air bombing and, at the end of 1915, the Ranken Dart was introduced. This was a specialised 1lb, steel-tipped bomb designed to penetrate the outer skin of a Zeppelin and explode. Then there was the Farnborough Fiery Grapnel. This was like a pair of grappling hooks with an incendiary composition. This was towed behind (and below) an aircraft on a cable, hopefully penetrating the envelope and exploding.
Brock, Buckingham and Pomeroy
By the middle of 1916, there were new developments in incendiary/explosive ammunition for .303" machine guns. Initially, there was a reluctance to use them as they contravened the Hague Convention4, but Germany's use of gas in April 1915 hardened the resolve to beat the 'Hun' by any means possible. There were three types used together as 'mixed incendiary' the effects of which complemented each other.
Developed by New Zealand engineer John Pomeroy in 1902, this explosive bullet was quickly adopted by British defence services as a means of combating the growing Zeppelin threat. Filled with nitro-glycerine the bullet ignited the hydrogen gas which escaped from the tear in the Zeppelin gas bag created by the bullet's passage.
The Buckingham bullet (Mk VII bullet) was an incendiary/tracer bullet based on phosphor, invented by James Buckingham in 1914. The bullet contained an incendiary filling which percolated through an annular hole, the seal of which melted on firing, the phosphorus igniting on contact with the air.
An explosive bullet developed by Commander Frederick Brock RN and first successfully demonstrated in 1915, the Brock bullet was designed to explode between the outer covering and gas cells of an airship. Used by the RFC until 1917 and the RNAS throughout the Great War.
The first Zeppelin brought down on British soil descended in flames on the night of 2-3 September, 1916, all 16 crew members died in the conflagration. This victory came at a time when the Zeppelins had bombarded Britain with apparently no loss. The defences seemed inadequate and public opinion was scathing on the forces involved and people were terrified of Zeppelins. Morale was low. The hero was Lieutenant W Leefe-Robinson of 39 (Home Defence) Squadron RFC flying a BE 2c armed with an upward firing Lewis Gun. The drums were loaded with an alternate mix of Pomeroy and Brock and, despite apparently fruitless initial attacks, he succeeded in igniting the hydrogen gas. As it happened, the 'Zeppelin' was a Schütte-Lanz, SL 11, the wreckage of which became a magnet for sightseers. He was awarded the Victoria Cross. Another four were downed before the end of the year.
Continuing success of the defence forces forced the Germans to reconsider. They developed some high flying airships, the 'Height-Climbers', which could reach heights in excess of 20,000 ft, away from the Home Defence fighters and AA fire. Unfortunately, the crew suffered from intense cold and needed oxygen. The airframe also became brittle in the cold and there were a number of structural failures. They were not a success.
A total of 115 Zeppelins were used by the German military. They lost 53 airships and 379 highly trained officers and men and 24 airships were so damaged they could not be used again. In June 1917 the German military stopped using Zeppelins for bombing raids over Britain. Although a tremendous psychological weapon, they caused little damage to the war effort, however, a total of 528 people were killed (mostly civilians), and more than 1000 were wounded. During 1915 and 1916, the peak years, 115 were killed and 324 injured in London. In the rest of England, 361 were killed and 692 wounded.