Every commander of armies over the centuries has known that detailed information about the number and disposition of the enemy troops is essential if a proper plan of attack and defence is to be formulated. Hiding troops behind a topological feature so they may be to be brought into battle at the crucial moment has decided many a battle. The classical, often quoted, example is the Duke of Wellington's tactically critical move of hiding the British Guards on the reverse slope of a hill at Waterloo (1815). Accordingly, reconnaissance to determine the disposition of the enemy's forces has always played an essential part in warfare through the ages.
Observation and reconnaissance from the air, by overflying of the battlefield with manned balloons, has been utilised as far back as the French Revolution, the American Civil War and the Boer War. In all of these three wars, the balloons were vertically oriented, tear-shaped, inflated by hot air and were used for directing artillery fire. The observer was suspended in a wicker basket, but when the balloon was not securely tethered to the ground, (i.e. not captive) it was highly susceptible to the vagaries of the wind.
By the beginning of the 20th Century, all modern armies had balloon aerial observation units and hydrogen, or illumination gas (coal gas), was being used as the lighter-than-air inflation agent for these tethered, or captive, gas-filled balloons. In 1911 the British Balloon Detachment became the Air Balloon Battalion of the Royal Engineers and then fell under the jurisdiction of the Royal Naval Air Service (RNAS), soon to be absorbed itself into the Royal Flying Corps (RFC) and then, in 1918, the Royal Air Force (RAF). However, the British Expeditionary Force (BEF) did not have a single observation balloon on its strength when it arrived on the Western Front.Once the war on the Western Front became static and degenerated into trench warfare: everything went underground. The need for finding the dispositions of the now largely hidden enemy troops became the sine qua non.
From the outset of warfare on the Western Front, the Germans had observation balloons, but they also had the advantage of being the occupying power and thus they usually ensured that they occupied the higher ground: even if this meant, initially, they had to cede some ground to the Allies. The German dominance of the Ypres Salient in Flanders, Belgium, being an example how they were able to control territory from the advantage of over-seeing, from the surrounding hills, the terrain below. From these vantage points the Germans were able to inflict nearly four years of virtually constant directed bombardment on the hapless British troops in the Salient. The only way the British could even try to equalise the situation was to use captive observation balloons.
A potential rival to the observation balloon in 1914, was the recently invented (1903) heavier-than-air aircraft and much of the British reliance on reconnaissance derived intelligence was based on the efforts of these aircraft. Unfortunately, at the outbreak of the Great War, these primitive aircraft were neither stable nor reliable enough for this purpose. And the numbers that were available were very meagre. At the out break of war, the British could only muster a total of 113 military aircraft, and even some of these had been requisitioned from their civilian owners. The Germans and the French were a little better off with, respectively, 420 (including 36 Austrian) and 138 military aircraft. Later in the war, and particularly from 1917 onwards, reconnaissance and aerial photography aircraft played a vital role in the surveillance of the enemy lines.
Kite balloons and Drachens
As 1914 turned into 1915, all the belligerent nations on the Western Front had moved observation balloon units to the new front lines. The first British Kite Balloon Section arrived on the 8th May 1915 in the Aubers Ridge Sector, although some of the British High Command still had their doubts about their usefulness. It was several weeks before they were convinced of their efficacy, if not their vulnerability. Also, the relative inefficiency of the heavier-than-air aircraft with its cumbersome Morse code apparatus and limited flying time became quickly apparent.
The kite balloons were usually located 5.5-km metres (3 miles) behind the front line trenches at a distance apart of 20 to 25km (12 to 15 miles). At these bases they would await suitable wind and weather conditions so the observation balloons could ascend bearing a tethering cable and a telephone line. The optimal operating altitude varied between 1,000 and 1,500 metres (3,000 and 4,000 feet). Sometimes a group of three or four balloons were sent aloft simultaneously. In view of the distance that the balloon sections were located behind the front-line trenches, this normally took the tethered balloons clear of effective small arms and artillery fire.
When it comes to describing these military balloons there is an immediate confusion about names and terms. And the construction of the various types of balloon is amazingly complex. Often they are recorded as kite balloons. The 'kite' referred to here should not be confused with the Box Kite; a contraption, invented by Samuel F. Cody in 1901 and made of fabric supported by wood or metal poles to make a semi-rigid (when filled out by the wind) box-like structure. From this large man-sized box kite - or often a series of box kites in tandem - was tethered a harness into which the observer would be strapped and hoisted aloft. And, indeed, during the Great War, box kites were used from German submarines - U-boats - for observation and reconnaissance purposes in the open sea. Just how hazardous this must have been can only be imagined from our own experience of the unpredictability of flying even the best of kites in the park.
The kite balloon used on the Western Front at the beginning of the war was basically a large cylindrical gas-filled bag with hemispherical ends from which, at the rear-end, was suspended a rope. Along this rope were attached a series of umbrella shaped fabric parachute-like wind-catchers, somewhat analogous to tails fitted on children's kites; hence one source of the name 'kite balloon'. The second source of the name kite balloon is said to come from the angle (30 to 40 degrees) at which the balloon was flown respective to the ground - approximately the same angle as a kite is flown on a string. (For simplicity sake we shall use the term 'balloon' for all the gas-filled observation balloons deployed on the Western Front). Other balloon types used different types of fabric stabilisers - called steering bags - integrally attached to the tail end of the balloon.
These steering bags hung limply in still air until filled by the wind when they inflated and gave a stabilising effect to the whole balloon. Many of the early military balloons used on the Western Front were sausage shaped being cylindrical and rounded at both ends; indeed the British troops nick-named them 'Sausages' (or Ruperts) and the French, Saucisse. However, some were more of an elongated teardrop shape, horizontally orientated, with tail stabilisers located at the tapered rump end.
The French used their rather ancient spherical observation balloons in the early days of the War, whilst the Russians also employed them on the Eastern Front. These ball-like balloons had the unfortunate characteristic of rotating on their vertical axis, making the continuous observation of a fixed location very difficult indeed.*
By the end of the war the Italians had developed a spherical balloon which had stabilisers to avoid the inherent tendency to rotate. It was very stable in high winds and could rise to unprecedented operational heights. Had the war not finished when it did, there is little doubt that this technically superior type of observation balloon would have been adopted by all the belligerent nations.
The making and operation of an observation balloon
The sausage shaped balloon of both sides on the Western Front was around 200 feet (60m) in length, 50 feet (15m) feet in diameter, and contained about 30,000 cubic feet of highly inflammable hydrogen gas. Some of the larger balloons were filled with coal gas, also then known as illumination gas.
Most observation balloons had an external envelope made of sheets of rubberised (gutta percha = latex rubber + naphtha) diagonal cotton cloth, sewn together as gores and segments. The rubberised cloth was then vulcanised. Inside the envelope so formed, were located cylindrical hydrogen gas-bag(s) and a balloonet, which was filled with a constant supply of air from the wind further tautening and stabilising the envelope.
A valve attached to a fixed chain inside the balloon would be activated when the balloon expanded an was in danger over-inflating as it ascended, or warmed in the sun, releasing gas so the balloon would not burst under its own pressure.
Due to paucity of suitable dyes, the balloons were usually coloured yellow or grey with chrome or aniline dyes.
Helium, an inert gas, and, therefore, potentially a much safer balloon inflation agent, was not available in large quantities until just before the Armistice and was never put into operational use on the Western Front in the Great War.
The shape of the stabiliser at the rear end of the balloon often gave the nickname to the balloon. A typical example of the sausage-type was the not very successful German balloon designed by Major John Parseval and Hauptman von Siegsfeld almost thirty years before the Great War. It had a single stabiliser (or balloonet) that was tube-like, located low and centrally and curved over the tail of the balloon. It was officially called the Drachen - German for Dragon or, also, a Kite (more confusion!) - and unofficially as the Nulle or the 'Testicle' due to the suggestive shape of the air-filled steering bag. The size of this balloon was 65 feet long and 27 feet in diameter (20m x 8m).
Captain Caquot's balloon
An example of the increasingly favoured elongated tear-shaped balloon, streamlined in form with three rounded rear mounted stabilising fins, was the French Caquot (pronounced Kah-Koh and designed by Lt. Albert Caquot). It had the unique design feature of holding the hydrogen gas in critically sited chambers within the envelope of the balloon, whilst the tension and rigidity of the envelope was ensured by open-ended air chambers. These allowed air to enter the main balloon chamber to make up any volume deficiency that may have occurred due to the loss of the hydrogen gas. This could occur through seepage, or changes in volume due to atmospheric pressure and temperature variations. The arrangement of the gas chambers within the envelope allowed the Caquot to ride in a more stable manner above its mooring, and lessened the tension on the tethering cable.
The Caquot was of the shape that older readers will associate with the description 'barrage balloon' in the Second World War. Because of the better stability and performance of the Caquot at higher altitude, the Germans soon copied it, calling their version the 'Type Ae 800'. The British took delivery of numbers of the Type M and the Americans manufactured large numbers of this type of balloon (around 1,000) in the USA. As the war progressed the Caquot type almost entirely replaced the Drachen type design in all the armies.
The original Caquot was 28m long (92 feet) and 10m (32 feet) in diameter and cost ?450. It had a capacity of around 23,200 cubic feet of hydrogen gas. It could support two observers and their telecommunications and mapping equipment at an operational level of between 300m (1000 feet) and 1,200m (4000 feet). It is said that at this upper height, in good clear weather, and with reasonably flat terrain, large objects at 80km (50 miles) distance could be spotted through binoculars. However, the normal, optimal, operational observation circle was about 10km (6.5miles) in diameter.
If conditions demanded it, the balloon could be flown at somewhat higher altitudes. It was also robust enough to be used in windy conditions. It is said up to 110kph (70mph) could be managed, although most 'sausage' balloons were taken out of service when the wind speed rose to higher than 55kph (35mph).
In any event, the occupants must have endured a very bumpy ride on occasions, with airsickness being an almost constant occupational hazard of a balloonist.
Tethering and manipulating the captive balloon
One end of the 15mm (5/8th's of an inch) diameter cable, that tethered of all types of observation balloon, was attached to the under-belly of the balloon by multiple branch ropes with attachment points to a 'girdle'. This went all the way round the long axis of the balloon. It provided a bracing effect, and enhanced rigidity and stability. The other end of the cable was wound onto a winch that was bolted to the back of a 3-ton lorry and powered by a petrol engine. This winch would be used to pay out the balloon cable as the balloon rose in the air - nominally at about 10 metres per second - and to reel it in when the observation missions were accomplished. Later models were provided with express speed winches so that when danger threatened - as it frequently did - the winch could within seconds, rather than minutes, reel in the balloon and its occupant(s).
The balloon crew also had access to a valve in the nose of the balloon that could release gas and expedite the descent of the balloon. Another device, self-explanatorily called the 'ripper panel', could be removed by the balloon crew in even greater extremis; it would cause the balloon to descend even more precipitately.
The anticipated 'life' of an observation balloon in an active sector of the Western Front was about two weeks. By 1918, due to the activities of the air aces called 'balloon-busters' the 'life' of a balloon could be as little as half a day. These aces called the men who manned the balloons, 'balloonatics'.
The strength of a British Field Balloon Company was usually 5 or 6 officers (four of whom served as observers in addition to their regimental duties on the ground) and between 150 and 200 other ranks. Each balloon had 48 men to handle it. These men required a high level of training, strict co-ordination and a high level of discipline, since the balloon on the ground could be an exceedingly dangerous object if not kept under full control at all times. Other responsibilities included moving the balloon between operational sites and guarding it. Each Balloon Section was expected to be militarily self-sufficient in its routine daily duties.
Due the paucity of the number of Balloon Sections, and the constant need for the vital function they performed, the troops manning them routinely spent long periods in the War Zone without the benefit of the relief patterns of the infantry.
Equipping an observation balloon
The traditional woven balloon observer's basket or gondola, of willow and bamboo, was universally used by all the Western Front balloon crews due to its lightweight and sturdiness. Its floor dimensions were 3 feet x 5 feet, and its height 4 feet (0.9m x 1.5m x 1.2m). In British Army parlance, it was called a 'car'.
The equipment carried by a British Western Front balloon for a crew of two balloonists (usually the balloon commander and the observer) has been variously recorded as including :
- a telecommunication apparatus with two telephone handsets;
- two pairs of binoculars;
- two long-range cameras (the balloon provided a stable, vibration free platform which the contemporaneous aircraft could not match);
- two sheath knives (the purpose of which can only be conjectured);
- two lifesavers (ditto);
- an aneroid barometer;
- an airspeed indicator;
- four sand-bags;
- a map-board with appropriate maps and blank sheets for drafting;
- a pressure gauge;
- a code book;
- two parachutes (also see below);
Plus, no doubt, a thermos flask of hot British Army tea and some sandwiches. We may also be confident that, on occasion, a hip flask of something rather more fortifying was carried aloft, for medicinal purposes!
Depending upon the operational requirements, the balloon may have carried additional hand signalling equipment (with an electrical signalling apparatus for night operations) and the means of direct telephone connections to various executive officers and headquarters.
The men who manned the balloons and their life-saver
That the jobs of the balloon commander and observer were hazardous in the extreme is self evident, and casualties were correspondingly high. Until 1915, the British did not have parachutes. That year the Spencer Static Line (Automatic) Parachute was introduced on the Western Front. It was attached to the outside of the balloon basket and operated using a static line as the balloonist leapt clear of the basket and rigging. But even these were considered of dubious reliability and only resorted to in extremis as there was a huge risk that the parachute would snag on the rigging of the balloon, or be set on fire by burning pieces of the balloon envelope.
Indications of the reservations with which the reliability of these parachutes was regarded, can be appreciated when it is known that when a new model was tested in 1916, its designers named it optimistically as 'The Guardian Angel'. Many balloon crews died when their highly inflammable hydrogen-filled balloon was set on fire, and fell precipitously to earth, leaving little chance for the crew, even if their parachutes did open. The Germans alone are said to have lost around 250 observation balloons on the Western Front: an average of five a month for the duration of the War.
The tasks of a balloon observer
The tasks of the balloon crew when aloft required skill, a cool head, patience, fortitude and not a little courage. It involved mapping and counting (or estimating) troop concentrations, locating artillery pieces and gun-sites and the gathering of any information that might be relevant or useful to the army commanders on the ground.
Overall, the most important activity concerned shell spotting. This was achieved by spotting the muzzle flashes of the enemy's guns, or observing the trajectory of the larger shells in flight, and by recording the accuracy of 'friendly fire'. Later in the war, sophisticated techniques enhanced the observers' ability to spot gun-flashes and even locate the enemy's guns by their sound. The crew in the balloon would be in constant touch with the artillery, and would range their shots so that the salvos could be accurately placed on key military features. They could also inform the artillery of active enemy guns, or batteries, so counter-strikes could be mounted. Presumably, the balloon crew could even see their own possible fate hurtling towards them when the observation balloon was targeted by artillery or tracered small arms fire.
The possibility of hitting a balloon, or its basket, with an artillery shell must have been exceedingly difficult in three-dimensional space at the operating altitude of the balloon. Presumably, a shell that was accurate would pass through the balloon without exploding, unless very sensitive contact fuses were present, which they certainly weren't in the early part of the Great War. Due to the volume of the gas and air in the balloon, even though the hole(s) in the envelope might well cause the balloon to collapse, there could be time to winch the balloon down to safety - at the normal winch speed this took about 10 minutes - or the for the crew to use their parachutes.
Although observation balloons were also occasionally shot down by small-arms fire, this was surprisingly difficult to achieve due to the distances and altitude involved. Ordinary rifle and machine gun bullets would pass relatively harmlessly through the hydrogen gas bag, causing damage but not immediate destruction. Hits on the balloonist's rather flimsy woven wicker car would be an entirely different matter.
When fighter aircraft became more sophisticated, and could carry out the necessary aerobatics required to safely target the observation balloon, many attempts were made to shoot the observation balloons down. It was not until the special incendiary machine gun bullets - the so-called Buckingham Bullets, of which the flat-nosed .45 calibre was the most effective - designed to bring down the Zeppelin airships over England, became available on the Western Front in 1917, that any degree of success was achieved. Early attempts by the French in 1916, using the specially designed 4.5 feet (1.4m) long le Prieur rockets (la torpeille), had some success. (The rockets were attached to the wing struts of a bi-plane and fired electrically by the pilot from his cockpit). Willy Coppens, the Belgian air-ace, claimed 37 balloon kills and was the top balloon-ace of the War (although some records give this distinction to the French ace Lieut. M. Coiffard with 28). In September 1918, an American fighter pilot, Lt. Frank Luke downed 14 German balloons in 17 days*.
*N.B. This claim is typical of the uncertainty that surrounds much of the apparently detailed information about the Great War. The actual balloon score credited to Lt. Luke varies from source to source, confusion often arising from the combination of balloon kills with aircraft kills: also, an unknown number of balloon kills were shared with a fellow American, Lt. Joseph Werner. The maximum number of balloons credited to Lt. Luke is 19 and the minimum 14: the latter figure - verified by the website of the Luke Airforce Base, Arizona, USA - seems to be the correct score. Unfortunately, the citation for Lt. Luke's posthumous award of the US Medal of Honor (1919), does not clarify this point: one might reasonably expect it to do so.
Of course, every attempt was made to protect the balloons by supportive action from the ground and the air. Every balloon site was surrounded by anti-aircraft artillery and high-powered machine-guns, and had a shield of fighter planes. Chains and cables were suspended from the balloon to make further hazards for the enemy fighter aircraft and, where the balloons were gathered in a group, a sort of chain mail was linked between them. The Germans skilled use of a spectacular incendiary anti-aircraft shell was said to deter all but the most ardent of the Allied fighter pilots.
Paradoxically, the closer a balloon was winched down to the ground, the safer it became, as most pilots would not attack below 1,000 feet altitude for fear of anti-aircraft and small arms fire.
At the time of planned infantry offensives, the fighter aircraft squadrons of the side launching the offensive were specifically instructed to target the enemy's observation balloons, so as to blind the enemy field commanders to the movements and dispositions of the attacking troops.
The changing role of the observation balloon
As the war progressed, the development of more technically sophisticated aircraft allowed them to take over much of the day-to-day reconnaissance and photography work, leaving the balloon observers to concentrate on the monitoring of the Allied and German artillery. This latter task was difficult to carry out from aircraft over extended periods. So the observation balloon retained its usefulness even in the last year of the war, as the introduction of more sophisticated ranging techniques allowed mathematical predicting of the ranging of the guns and their more efficacious deployment. At the end of the war the British had 44 operational Balloon Sections plus 37 Sections in reserve whilst the French and Belgians had 72 and 6 compagnies respectively. The Germans had 177 Baloonzug but only about half of these were fully operational. The relatively new arrivals - the Americans - had six Balloon Companies in France by the end of November 1918, with another 70 en route.
After the war was over, it was realised that, were it not for the information provided by the observations of the balloonists, it would have been immeasurably more difficult for both sides to prosecute the war when the belligerents were largely hidden below the horizon and ground itself.
Indeed, it was ventured by some historians that had this balloon technology not existed at all, the war must inevitably have come to an early conclusion, or a negotiated stalemate, long before reconnaissance and photography aircraft could have become a really meaningful alternative.