If I say the word “balloon”, the image that pops into your head is likely a benign one – a colourful helium party balloon, perhaps; or a hot air balloon drifting serenely over a city. But, as with pretty much all of mankind’s creations, these seemingly docile flying machines can and have been turned into weapons of war. As we’ve previously covered in our video The Fascinating Tale of the World’s First Air Force, from the Napoleonic Wars of the late 18th and early 19th Centuries all the way to the First World War, tethered observation balloons were widely used to scout enemy defences and direct the fall of artillery fire; while today balloons still play a key role in military communications and intelligence gathering. Balloons have also been used in more directly offensive roles, the most famous example being the Japanese Fu-Go campaign of WWII in which nearly 10,000 hydrogen-filled paper balloons were launched across the Pacific towards North America. Armed with incendiary charges, Fu-Go were intended to set fire to forests on the American west coast. More on this fascinating tale and the bizarre results of this rare direct attack on the U.S. mainland during the war in the Bonus Facts in a bit. But the Japanese were not the only belligerent nation to use balloons as a weapon of war; halfway across the world, the United Kingdom also launched its own balloon offensive, which proved shockingly effective. This is the story of Operation Outward, Britain’s forgotten balloon blitz.

The idea for Operation Outward came about largely by accident. Throughout the Second World War, Britain, like many other nations, made extensive use of barrage balloons to defend cities, factories, naval bases, and other strategic targets. These were large, kite-shaped hydrogen balloons tethered to the ground by steel cables. Attacking aircraft flying below the balloons risked having their wings sheared off by the cables, while flying higher to avoid them resulted in poorer bombing accuracy. However, in high winds barrage balloons sometimes broke loose and drifted across the countryside, wreaking havoc as their trailing mooring cables shorted out power cables and other electrical infrastructure. In early 1940, such incidents prompted Air Vice Marshal Owen Tudor Boyd, head of the Royal Air Force’s Balloon Command, to note:

“Since the outbreak of the war, I have had constant complaints from the electricity distributors regarding the damage done in this country by [barrage] balloons that have broken away from their moorings…advantage might be taken of this to impede and inconvenience the enemy.”

Boyd proposed launching bomb-carrying balloons from France, to be carried over Germany by the prevailing winds. The positions of the balloons would be tracked via radio triangulation, and the bombs dropped by radio command when the balloons drifted over a worthwhile target. Boyd’s plan was met with significant skepticism, with some critics arguing that such weapons were ungentlemanly and that, in the most British way to say it possible, “…attacks of this nature should not be originated from a cricketing country”. Others feared that such an attack would lead the Germans to retaliate in kind. In the end, however, the fall of France and the evacuation of the British Expeditionary Force from Dunkirk in June 1940 rendered the whole debate moot.

Yet not long afterward, another freak event revealed that Boyd’s plan might yet still be feasible. On the night of September 17, 1940, a number of barrage balloons broke loose in a gale and drifted across the North Sea to Denmark and Sweden, where they shorted out power lines, blocked railways, and even knocked down a radio transmission tower. When reports of the damage inflicted reached the British War Cabinet a week later, Prime Minister Winston Churchill demanded that the use of offensive balloons against Germany be investigated. With the Army shut out of mainland Europe and British cities suffering near-daily bombardment by the Luftwaffe, Churchill was desperate for any means – however unorthodox – of striking back against the Germans.

The British Air Ministry was initially skeptical, arguing that free balloons were too inaccurate and too expensive to be a feasible weapon. They also reiterated earlier warnings about possible German counter-attacks. Meanwhile, the Admiralty was much more enthusiastic, with the plan’s greatest champion being Captain Gerald Banister, Director of Boom Defence for Royal Navy harbours. Banister pointed out that winds above 16,000 feet or 5,000 metres tended to blow from west to east, making it very difficult for the Germans to retaliate in kind. Furthermore – and more importantly – the Navy had in its storehouses some 100,000 2.4-metre latex weather balloons that were otherwise surplus to requirements and could easily be pressed into service.

Banister’s plan, soon dubbed Operation Outward, called for the balloons to trail long metal wires which, like rogue barrage balloons, would short out any high-voltage power lines they drifted across. This would trip circuit breakers, overheat and damage the power lines, and even start fires. And while the German power grid was largely protected against being shorted out to the ground, it was very vulnerable to shorts across the different phases of the transmission lines. Trials conducted in Britain as well as a survey of the German electrical grid not only revealed that the balloons would be highly effective against electrical infrastructure, but that they had a 10-75% chance of encountering high-voltage power lines during a 50 kilometre flight along the ground.

To time the balloons’ flight across the North Sea, they were fitted with a crude ballast control mechanism. At launch, a piece of slow-burning fuse was lit, timed to burn out over German-occupied territory. As the balloon rose, decreasing air pressure caused the envelope to expand until, at around 25,000 feet or 7,600 metres, an internal cord halted the expansion and the balloon’s ascent. A pressure release valve then opened, slowly releasing hydrogen gas and causing the balloon to gradually descend towards its target. Finally, the fuse burned out and released the bung on a can of mineral oil, which dripped out, lightened the balloon, and halted its descent. The fuse also released the power-line shorting cable, consisting of 200 metres of hemp cord attached to 90 metres of 15 gauge steel wire. The balloon then drifted along just above the ground until it encountered power lines.

While the original Operation Outward plan was designed to attack electrical infrastructure, incendiary payloads were soon added in the hopes of igniting large areas of German pine forest and heathland and diverting hundreds of people to firewatching and firefighting duties – people who might otherwise be employed in more vital war work. Three different kinds of incendiary payloads were devised, codenamed Beer, Jelly, and Socks. Beer comprised a basket containing 7 or 8 No.76 Special Incendiary Grenades – also known as Self-Igniting Phosphorus or SIP Grenades. Developed for use by the Home Guard – Britain’s emergency anti-invasion force, the SIP was a half-pint glass bottle filled with white phosphorus, benzene, and a strip of crude rubber- the latter of which gradually dissolved to render the mixture sticky like napalm. When the slow-burning fuse on the Outward balloon burned out, the basket was released, dropping the grenades onto the target. On hitting the ground, the glass bottle shattered and the white phosphorus ignited on contact with air – and for more on this and other weird and wonderful weapons used by the Home Guard, please check out our previous video The Badass Story of the Dad’s Army.

Jelly incendiaries were rectangular 4.5 litre metal canisters filled with jellied gasoline – AKA napalm – while Socks were long, thin canvas bags packed with sawdust, soaked in paraffin wax, and fitted with fuses. Three socks were connected together to form a triangle designed to catch on the crown of a tree and set it alight. Two other payloads, codenamed Lemon and Jam, were also developed, the former containing a small explosive charge and the latter propaganda leaflets. The Lemon bombs were actually left over from an earlier scheme codenamed Operation Albino, which involved releasing large numbers of explosive-armed balloons to take down intruding enemy aircraft.

In all, each Outward balloon would cost only 35 shillings – around £120 today – to manufacture, while the whole operation would involve only a few hundred personnel. The shoestring nature of the project was a large part of its appeal, for the cost in fuel, ammunition, and aircraft maintenance needed for the Germans to shoot down a single balloon would always exceed what it cost for the British to launch it. So even if Operation Outward inflicted little physical damage, it would still be an effective economic weapon. Thus, despite continued opposition from the Air Ministry, Operation Outward was approved by the British Chiefs of Staff in September 1941 and a launch site set up near HMS Beehive, a Royal Navy shore establishment near Felixstowe in Suffolk.

Given the cover designation of a “Boom Defense Unit”, the entire organization comprised a little over 230 people: six Royal Navy and Royal Marines officers, 80 Royal Marines, and 147 members of the Women’s Royal Navy Service – better known as the Wrens. Support was also provided by RAF Balloon Command – who supplied the hydrogen gas to fill the balloons – and the Naval Meteorological Service. Balloons were launched from the nearby Felixstowe Ferry Golf Club, with the balloons being filled from truck-mounted hydrogen cylinders inside canvas tents or plywood windbreaks. Though this may seem a rather benign assignment, it did in fact have its dangers, as former Wren balloon launcher Antoinette Porter later recalled:

“The balloons were packed in french chalk which got into the back of your throat rather badly. We used to put the residue on the floor and, during our cocoa break, slide up and down and fall over… These monstrous balloons were housed in three sided tents which, as inflation progressed, created friction…balloon to canvas…causing a great risk on instant combustion. So out came our buckets and stirrup pumps and we sprayed balloon and tent. As the nearest tap was 100 yards away we were all forced into a chain gang…[yet] in spite of our simple precautions [anti-flash hoods and fireproof gloves]the balloons did, quite frequently, explode causing the nearer Wrens to be flash burned and the further ones to get an instant sun tan with singed eyebrows and hairline. Fortunately I was never near enough to get badly burned but many of my pals were not so lucky and were carted off to Trimley St Mary Hospital to be plastered with gentian violet or acriflavine…not a pretty sight!”

Yet the Wrens took such hazards in stride, bringing to their unusual duty the kind of patriotic cheekiness that characterized the British wartime spirit:

“We also wrote (very tame but we thought very daring and rude) messages on the balloons to Hitler, Goering, Goebbels and any other poor German who saw them. And of course, the black messages, when inflated, became very large. I remember such things as, ‘Death to all Germans’, ‘Balls to Hitler,Goering and Goebbels’, and, ’Take this you Bastards’…One Wren brought a battery radio which endlessly churned out lovely music… [including] ’I don’t want to set the world on fire’ which we adopted as own Boom Defence song and sang in our lorries.”

Once filled, the balloons were carried to another part of the golf course to be fitted with their payloads. The slow-burning fuses were then lit, and the weapons released. For ideal wind conditions, balloons were typically released between the hours of 10 AM and 4 PM.

The first launches took place on March 20, 1942. Within days, dozens of reports began trickling in from the Continent about forest fires and power outages inflicted by Outward balloons. Many of these reports came from local resistance movements, while others were gleaned from newspaper articles in Nazi-occupied countries, where the German authorities tried to spin the British attacks in a negative manner. The operation’s greatest success came on July 12, 1942 when a wire-carrying balloon struck a 100 kilovolt transmission line near Leipzig. The circuit breakers at the nearby Böhlen power station failed, causing one of the 16.5 megawatt generators to be thrown out of synchronization. The rotor began to vibrate until it finally bent and tore the generator apart, starting a fire that burned the station to the ground. All told, the 35 shilling balloon inflicted an estimated 1 million pounds of damage and knocked 250 megawatts of generating capacity offline for months. A more common – if less spectacular – occurrence was for a balloon to short out and sever one or more cables on a transmission line, creating unbalanced forces that caused the whole electricity pylon to collapse.

And there was more good news, for Allied intelligence learned that the Germans were deploying up to 250 fighter aircraft per day in an attempt to shoot down the Outward balloons – an expenditure of resources far in excess of the balloons themselves. Large numbers of personnel were also being diverted to fire watching, firefighting, and electrical repair duties – just as the Operation Outward planners had intended. Better still, German efforts to protect electrical infrastructure against the wire-carrying balloons proved largely ineffective. At first, the authorities issued orders to shut down power lines in the bath of drifting balloons and to increase the sensitivity of circuit breakers. However, these measures proved difficult to implement and led to even more power disruptions. In an attempt to prevent electricity pylons from collapsing, the Germans also developed a new kind of cable clamp that would let the cables fall to the ground if subjected to large unbalanced loads. But ice buildup or wind also caused the clamps to release, once again resulting in widespread power outages. Worse still, because the clamps had been designed by a prominent member of the Nazi party, it took months for their effectiveness to be questioned and the original clamps replaced.

Buoyed by these successes, in July 1942 the British Admiralty established a second launch site at Oldsters Bay near Dover and a third at Waxham in Norwich. By August, Wrens at all three sites were launching up to 1,800 balloons per day. But it wasn’t all smooth sailing. Being unguided, the Outward balloons were an indiscriminate weapon, and many ended up drifting over neutral territories. For example, on the evening of January 19, 1944, two trains collided in Laholm, Sweden, when an Outward balloon knocked out lighting on the railway. On another occasion, a group of Outward balloons got caught in an eddy and drifted back towards England, knocking out the power grid in Ipswich. British citizens also often mistook the balloons for German parachutes, triggering numerous local invasion scares. Finally, there were also internal difficulties, with the Air Ministry and the Admiralty constantly bickering over control of the project – because of course they did. However, as the Navy had the surplus balloons and the Air Force the hydrogen to fill them, the two services had no choice but to grudgingly cooperate.

But as air operations over Europe intensified in the lead-up to D-Day, it was feared that Operation Outward balloons would pose a significant danger to Allied aircraft. As a result, from May 1944 balloon launch operations were significantly scaled back, the mass launches being replaced by a “trickle” of balloons launched at 10 minute intervals. Wire-carrying balloons were also all but eliminated, replaced with incendiary balloons which posed little danger to aircraft. Furthermore, this new system freed up hydrogen supplies for use in barrage balloons, which were desperately needed to protect the invasion beaches in Normandy and defend against the German V-1 flying bomb offensive – and for more on the latter, please check out our previous video A Wingtip and a Prayer: the Insane Way British Pilots Defeated Germany’s Secret Weapon. But as the Allies gained air superiority over Europe and pushed their way closer towards Germany, Operation Outward became increasingly redundant, and the last balloons were launched on September 4, 1944. In total, 99,142 balloons were launched over the course of 899 days, split evenly between wire-carrying and incendiary types.

But what did Operation Outward actually accomplish? Surprisingly for such a crude weapon, quite a lot. Though official records are rather spotty due to official censorship and the destruction of documents near the end of the war, Outward balloons caused over 500 major power interruptions in Germany and 5,000 in occupied France, and started hundreds of forest fires across Europe. A 1946 report estimated the total damage inflicted at £1.5 million – nearly £58 million in today’s money – and that’s not including the significant resources and manpower diverted by the Germans in a futile attempt to counter the British Balloon Blitz. As Captain Gerald Banister’s final report concluded:

“…the evidence obtained shows that these Outward attacks were a continual menace to the whole German electric supply system for even minor incidents caused continual interruptions to the power supplies with damage to the equipment involving diversion of manpower on repair work, to say nothing of production delays. The destruction of Böhlen alone however was an ample reward for these operations…the result of the operation was out of all proportion to the man-power and material employed.”

In other words, Operation Outward was a perfect example of the unconventional, make-do-and mend approach to warfare that served the British so well throughout the conflict. Indeed, it is a testament to the effectiveness of the British approach to balloon warfare that the only real strategic success of the Japanese Fu-Go program was when, on on March 10, 1945, a lone balloon shorted out high voltage transmission lines near Toppenish, Washington State. This temporarily knocked out power to the Hanford Engineer Works, which produced the Plutonium used in the atomic bomb dropped on Nagasaki.

And the basic principle of the Outward Balloons is still used today in the form of “graphite” or “blackout bombs” such as the American BLU-114B. Dropped from aircraft or delivered by guided missile, graphite bombs burst and scatter thin carbon-fibre filaments over their targets, shorting out and disabling electrical infrastructure. Such weapons were widely used by Coalition forces in 1991 Persian Gulf War to knock out Iraq’s power grid, and again by NATO against Serbia during the 1999 Kosovo conflict. And in more recent years, South Korea has also developed an arsenal of graphite bombs as a safeguard against invasion by the North. It just goes to show that a weapon doesn’t need to be complicated to be effective – and that the next time you’re given a helium-filled party balloon, it’s probably best to avoid walking near power lines.

Bonus Fact:

Going back to the Japanese balloons, Fu-Gos, called fire balloons in the U.S., were approximately 70 feet tall, 30 feet in diameter and, fully inflated, held about 19,000 cubic feet of hydrogen. Launched from the Japanese island of Honshu, they were ultimately found in many states including Alaska, Washington, Oregon, California, Arizona, Idaho, Montana, Utah, Wyoming, Colorado, Texas, Kansas, Nebraska, South Dakota, North Dakota, Michigan and Iowa. Some were also found in Canada and a few turned up in Mexico.

As for the impetus for them, through experimentation, Japanese researchers found that at just over 30,000 feet altitude, the jet-stream could carry a large balloon about 5,000 miles across the Pacific in three days in late autumn when the stream was strongest. They then developed an extremely clever, and simple, mechanical device to automate the flight of the balloons and release the explosives. To prevent too much fluctuation in altitude as the temperature changed in the night vs. the day, engineers created a system controlled by barometric sensors. If the altitude got too low, below 30,000 ft, a small charge would fire, ejecting two sandbags mounted on a spoked wheel containing other sandbags and the explosive devices themselves. When the temperature heated up in the day time and the balloon rose above 38,000 feet, barometric-controlled valves would automatically open, releasing hydrogen and thus lowering the balloon to the desired level.

The control system was set up to last just three days at which point (in theory) there would be no sandbags left, just the incendiary devices ready to be released once the balloon dipped below 30,000 ft. At this point, the balloon would theoretically be over the U.S. and incendiary devices ranging from 5 kg to 15 kg would be released. A fuse would also be lit which would burn for approximately 84 minutes before igniting the balloon itself with its 19,000 or so cubic feet of hydrogen then exploding.

The balloons themselves were made of “washi,” a tough paper made of mulberry bushes. It was only available in limited sizes, about the size of a map, so it was glued together with paste, often by teenage girls.

And so it was that in the early months of 1945, the American people were starting to notice that something strange was happening. Balloons and explosions had been seen in many states and seven balloons were handed over to the military by bewildered citizens. U.S. fighter planes tried to intercept the balloons but they were only able to destroy about twenty, as the balloons typically flew at very high altitude and were amazingly fast and difficult to track down once a report of one came in.

However, in the end these clever devices didn’t exactly have the intended effect. Of the 10,000 or so launched, Japanese military officials estimated only about 10% of them would reach America. Approximately 342 of the balloons were found or seen in North America, and the result was minimal property damage and just six people killed (we’ll get to that tragic story and how it likely easily could have been prevented had the government not governmented).

That said, had the balloons been launched in the summer, rather than late autumn and winter, they may have started significant fires as had been originally planned. Further, one incident involving a fire balloon could have had major implications on the war. The balloon descended on the Hanford Nuclear Reservation in Washington state, landing on power lines and cutting power to the nuclear reactor cooling pumps. Fortunately, backup generators restored power before there was any damage or a nuclear meltdown.

As for how the Japanese had managed to get the balloons into North America, this was at first something of a mystery. Most military officials didn’t believe they had come all the way from Japan. Many thought Japanese soldiers were coming ashore on North American beaches and launching the balloons. The mystery was solved when scientists with the Military Geology Unit analyzed the sand from some of the recovered sandbags, examining its microscopic sea-life and mineral composition, and determined the exact beach it had come from, which indeed was not in North America, but in Japan.

Despite the ineffectiveness of the balloons, authorities were still concerned. Their ability to start fires couldn’t be denied and there was also the potential psychological effect they could have on the American people. More importantly, they knew the Japanese had been working to develop biological weapons and a balloon carrying such payloads could potentially do major damage in that way.

To help get around the potential panic, people who found the balloons and reported it to the authorities were sworn to secrecy. In 1945 though, Newsweek ran an article on the weapons, and a similar story appeared in another periodical the next day. The U.S. Office of Censorship (yep, that existed for about four years) sent a notice to the media, asking them not to mention the balloons or balloon-bomb incidents.

Exercising their rights, the press of course continued to notify the U.S. public of the dangers of approaching such balloons if encountered… Or, actually, in reality they complied with the U.S. Office of Censorship and no further reporting was done on the balloons at this time.

This likely contributed to the single successful balloon attack of the war. A pregnant woman, Elsie Mitchell, her husband Pastor Archie of the Bly Christian and Missionary Alliance Church, and five Sunday school children were out for a picnic. While Archie was discussing good fishing spots with a couple construction workers who were working on the road where the group had stopped, Elsie and the kids went to search for a good spot for their picnic. In the process, they found one of the balloons.

Not knowing anything about it, the kids and Elsie went to investigate, with the last words Archie ever heard his wife say, according to the Oregon newspaper, The Mail Tribune, being “Look what I found, dear!”

Richard Barnhouse, one of the construction workers, reported to the Tribune what happened next: “There was a terrible explosion. Twigs flew through the air, pine needles began to fall, dead branches and dust, and dead logs went up.”

When the construction workers and Archie rushed over, they found Elsie and the children’s bodies on the ground around a gaping hole in the earth. Their clothes were on fire, which was quickly put out. All of them but one of the young girls, Joan Patzke, died instantly from the blast. Joan lived for a few minutes after, but then passed away.

After these deaths, the U.S. Office of Censorship rescinded their former blackout on mention of the balloons and the public was informed of them and told if they found any to keep their distance and contact the authorities.

After six months of launches, the balloon attacks stopped abruptly in April of 1945. Allied forces had blown up two Japanese hydrogen plants, cutting resources needed for the balloons. In addition, Japanese commanders, seeing the balloon attacks weren’t very effective relative to the resources expended, discontinued the program.

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