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Interservice Relations

During the entire program, there was constant sniping between the Admiralty, which ran Operation Outward, and the Air Ministry, which was responsible for fighter, bomber, and barrage balloon operations. It is not unusual to have interservice rivalries, but in this case it was carried to extremes, with each side pointing out the perceived foolishness of the other.

It is curious for an American used to simple salutations and closes in business letters to read the flowery wording used in these British military communications. Many messages began with “I have the honour to refer to your letter…,” and then conclude with “I have the honour to be, Sir, Your obedient Servant.” However, in the body of the message, the writer would criticize the recipient in the harshest terms.

For example, the director of plans was puzzled by the Air Ministry's intransigence in bringing up reasons not to pursue the project. In late 1941, he wrote “The obstructive tactics of the Air Ministry in this matter are only too obvious, though why they should wish to obstruct an operation which should reinforce their own bombing effort is difficult to understand.”

In a 1941 memo to the Vice Chief of Naval Staff, commenting on Air Ministry criticism of Admiralty plans, Captain Banister wrote “Referring to the attached memo, the disadvantages are only such as might have been expected to emanate from the Air Ministry and the statement in Paragraph 2(vi) is a typical example of their misrepresentation of facts.”


Unlike in the United States where freedom of the press is a basic right, in wartime Britain the government could issue stop orders, as it did in April 1942 when it demanded that all references about small drifting balloons be stopped. The military wanted to keep it under wraps in case they might need a similar weapon in the future. British newspapers were thenceforward restricted to simply reprinting reports published in European newspapers, all of which reported on incidents on the mainland, and not those in Britain.

As a result, the British general public knew very little about Operation Outward until the documents were declassified in the 1970s. It was because of this secrecy order that even the people who worked on the project could only receive recognition for having caused the enemy what was termed “…damage equivalent in naval parlance to the loss of a capital ship…”

Similarly, the electric supply industry wanted to publish details so that they could incorporate lessons learned from the German experience with disruptions into their own electric power system, but were also denied permission to publish.

German Acknowledgement of Damage

Because of wartime secrecy on both sides, it was not until the end of World War II that the effect of Operation Outward balloons (called störballons, or “disturbing balloons,” by the Germans) was known. However, there were some leaks, and intelligence acquired useful information during the war. There were reports about damage from the balloons from occupied France and as far to the east as Hungary.

In 1943, an internal German report acknowledged that high-voltage lines were being disrupted throughout the country. While, as expected, the report minimized the damage, it also pointed out that emergency crews were standing by to correct future incidents. Naturally, diversion of personnel and resources was precisely one of the intended effects of the program.

An extract from a late 1943 German 65th Infantry Division Special Q Orders reported:

The enemy is using recently balloons carrying beneath them spiral coils of wire with a hook at the end. If these balloons become entangled in power lines, serious shorts occur, and often the damage lasts for days, causing work of units and state of readiness to be held up…

Also, British intelligence received a report from occupied France that “reliable source reports balloons with hanging cables highly effective electric railways. Suggest continue.” They did.

Bohlen Bent Rotor

Figure 5. Bent rotor from the Böhlen power station near Leipzig that was destroyed by an Operation Outward balloon on 12 July 1942 (from The National Archives of the United Kingdom, folder #ADM 199–848)

German Attempts to Protect Power Lines

One of the problems for the Germans was when the balloons severed a line on one side of a power pylon, the resulting unbalanced mechanical forces on the tower or crossarms sometimes damaged the crossarms or even collapsed the whole tower.

The Germans developed a device to help prevent this additional repair burden—a new clamp that would let the power line conductors drop to the ground if there were large and unbalanced longitudinal pulls due to conductors breaking. Over a million of these clamps were manufactured. However, normal swaying in the wind or ice loading caused the clamps to disconnect the wires, causing even further damage. Because the new clamps were designed by a high-level Nazi engineer, it took some time for the transmission engineers to prove that his clamps were not a solution. Eventually, they were all removed and the original clamps re-installed.

The British learned that the Luftwaffe was sending up aircraft, in one case as many as 250 fighters, to shoot down the balloons and took that as a sign of their efficacy and that the Germans had not yet developed an effective countermeasure.


Because hydrogen was the gas of choice for all the British balloon projects, there were constant disputes over access to hydrogen supplies. As the June 1944 Normandy invasion approached and Allied air operations over Europe increased, Operation Outward received fewer and fewer permissions for balloon launches to avoid collisions between Allied bombers and the balloons. The ground rules were changed and the project was cut back to only a few balloons with wires a day, instead of fleets of hundreds, as had been the case. Eventually, in mid-1944, all hydrogen supplies were withdrawn, and the last balloons were launched on 4 September 1944.

Postwar Analysis

The balloon attacks were carried out between March 1942 and September 1944. During this time, the launching sites released 45,599 balloons that carried trailing wires. During the war, it was hard for the British military to collect detailed information on the balloons' effects. But there was an indirect source, because when balloons happened to stray into neutral territory and cause damage, there was strong diplomatic protest. Thus, the British concluded that if the balloons were doing their job in Switzerland and Sweden, they should be working in Germany as well.

After World War II, an assessment team from Britain's Central Electricity Board was sent to Europe to gather what information it could. The team learned that the balloon weapons had indeed been successful.

One of the most important instances of damage was the 12 July 1942 complete destruction of a power plant at Böhlen near Leipzig due to an Outward balloon that had been launched on 11 July 1942. A phase-to-phase short on a 110-kV overhead transmission line caused the circuit breakers to malfunction, causing one of the 16.5-MW generators to be thrown out of synchronism and begin to vibrate. Its rotor shaft bent, causing mechanical interference with the fixed stator, followed by an explosion and a fire that destroyed the power station. This event put 250 MW of generating capacity out of operation for an extended period. The value of that material loss was estimated by the team at £1,000,000 (US$4,250,000) in 1942 currency, not including the value of production time lost (see Figures 5 and 6).

The assessment team learned that the Germans realized the potential damage of the balloons and gave orders to shut down power lines in their path and make the circuit breakers more sensitive. However, the latter change made the system more sensitive to normal occurrences such as bird strikes and overloads and exacerbated the power outage problem.

Bohlen Interior

Figure 6. Interior of the Böhlen power station near Leipzig after the explosion and fire that destroyed the power station on 12 July 1942 (from The National Archives of the United Kingdom, folder #ADM 199–848)

There were far more incidents on the more common lower-voltage lines, some of which would suffer from multiple failures. Worse, even though the breakers might have been reset and power restored, the lines often suffered damage to the wires that would become apparent later under heavy loads or adverse weather, when they would break.

The team retrieved a report that showed that in the period from March 1942 through the end of January 1943, there were 520 major disturbances on German high-voltage lines of 110 kV and higher. In that same period, there had been about 25,000 Outward balloons launched. Belgian, Dutch, and French transmission lines also suffered. In France alone, over the entire program, there were 4,946 recorded incidents of power interruptions. The postwar assessment reports were quite specific in most cases about Operation Outward balloons being the cause of the damage cited.

The team's conclusion was “…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.” In another communication, the team wrote “the result of the operation was out of all proportion to the man-power and material employed.” In fact, in some months, there was more damage done to electrical systems by the balloons than there had been by bombers—and at a much lower cost to Britain.

During the war, the German headquarters reports naturally tried to put a happy face on the interruption events, but a report from engineers from the British Central Electricity Board on the team reported “that regional disorganization of electrical supply which had been dismissed as unimportant by the national load controller was, in fact, frequently widespread and serious.”

The Admiralty estimated the total costs for the operation at a little more than £2 (US$8.50) per balloon in 1942 currency. Even the Air Ministry had to opine that “The total damage caused by these attacks, particularly in view of the small effort expended, therefore, appears to be very high.”

After the war was over, in December 1945, Captain Banister wrote a letter summarizing Operation Outward and commenting on relations with the Air Ministry. In praising Sir E. Leslie Gossage, Air Marshall and commander of the Balloon Command, the source of Outward's hydrogen when supplies were scarce, he took the opportunity to point out that “the Air Ministry were using every excuse to obstruct the scheme…” This praise was not just politicking. Had it not been for Gossage's cooperation, Operation Outward would not have been able to obtain the necessary hydrogen for its balloons.

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