Sometimes small events have huge repercussions, as when a plane crash led Hitler to alter his French campaign plan of attack—and in the process confounded Allied defensive preparations.
In histories of the 1940 Battle of France, quarrelsome French generals and undisciplined soldiers typically receive most of the blame for allowing the Germans to make their breakthrough on the Meuse River. Equally important, however, was the French high command’s failure to adapt its war plans to cope with fallout from one of the most intriguing incidents of the “Phony War”: the Mechelen affair.
At midday on January 10, 1940, everything was still quiet on the Western Front that separated Belgium from neutral Holland and Nazi Germany. But as Belgian border guards at Vucht, near Mechelensur-Meuse, huddled over the stove in their guardhouse to escape the snow and freezing conditions outside, a drama unfolded in the air above them that was to have the gravest consequences not only for Belgium, but also for England, France, and Germany.
It began with a mistake made by a German aviator, Major Erich Hoenmanns, the fifty-two-year-old commander at Loddenheide air base, near Münster. He had been flying a Messerschmitt Bf-108 Taifun, a speedy four-seat courier and reconnaissance plane, from Loddenheide to Cologne when he lost his way in fog. While searching for the Rhine River, which he hoped would enable him to regain his bearings, he flew too far west and ended up circling Vucht near the Meuse River in Belgium.
At that point he appears to have inadvertently cut off the fuel supply to the plane’s engine by moving a lever inside the cockpit. The engine spluttered, then stopped, and Hoenmanns quickly decided that his only viable option was to land in a nearby field. The subsequent descent terminated with more of a crash than a landing: As he came down, the plane narrowly missed an electric cable, and its wings hit two trees as it sped between them. Nevertheless, although the plane was a write-off, Hoenmanns survived relatively unscathed.
Had Hoenmanns been alone in the plane, there would have been no dramatic consequences. He would have been interned for landing without permission in a neutral country, and that would have been the end of the affair. But he was not alone.
As has been confirmed by recently discovered documents in Reichskriegsgericht (German War Tribunal) files in the former Czechoslovakia, Hoenmanns had a passenger, fifty-year-old Major Helmuth Reinberger, whose position on the staff of Fliegerführer 220 made him responsible for masterminding the supplying of Fliegerdivision 7, the elite unit that was to land paratroopers behind Belgian lines on the first day of the imminent attack. He was traveling to Cologne to make sure everything was ready.
Reinberger had originally planned to take the train to Cologne, and had even purchased a ticket, but the night before he was due to travel he had bumped into Hoenmanns at the Loddenheide barracks, and had accepted his offer of a lift. Hoenmanns was pleased to have a passenger, and was unaware that Reinberger would be carrying Germany’s plan for its attack on Belgium. This document was at the heart of the German war strategy. On the very day when the two majors crash-landed at Vucht, Adolf Hitler decided that his attack, based on that same plan, should take place seven days later.
The newly discovered Reichskriegsgericht files highlight difficulties Hoenmanns was experiencing that may well have contributed to the errors he made in the cockpit. Some appear to have been the indirect result of his physical separation from his wife. She had remained in Cologne when, at the end of September 1939, he had taken the job in Loddenheide.
Her absence had given him the opportunity to acquire a mistress. Nevertheless, he kept up appearances by frequently flying to Cologne to visit his wife. His flying visits did more than preserve marital harmony. He wanted to escape from his desk job by becoming a fulltime Luftwaffe pilot. Although he had a license to fly civilian aircraft, his military pilot’s license had lapsed, and he needed to fly a certain number of hours to regain it. The flight time logged during the visits to and from Cologne was helping him reach this target.
His superiors at Loddenheide usually allowed him to borrow a plane for these flights, but the Reichskriegsgericht documents suggest that they only sanctioned them because they believed the flying enabled him to do his job more efficiently. As he flew over other air bases, he could see how their runways had been camouflaged, and his commanders hoped this would give him some new ideas on how to arrange camouflage at Loddenheide.
However, on the morning of January 10, this synergy, which had in the past kept everyone happy, began to fall apart, and Hoenmanns found himself pulled in two directions. On the one hand, he knew that Reinberger had an important meeting to attend in Cologne and was expecting to be flown there on time. He had told Reinberger that he hoped to take off at 10 A.M. His wife was also expecting him in Cologne.
On the other hand, one of Hoenmanns’ superiors wanted him to show some troops around Loddenheide; thanks to Hoenmanns, the airfield had been camouflaged so creatively that from the sky it looked like a working farm, and he was supposed to tell his visitors how he had achieved this effect.
Hoenmanns’ attempt to resolve the conflict by instructing a subordinate to show the troops around ended with his being reprimanded by his superior officer. That precluded Hoenmanns from asking for permission to fly to Cologne, and also delayed his and Reinberger’s takeoff. No doubt feeling guilty on both counts, Hoenmanns nevertheless went ahead and borrowed a plane for the flight without asking his superior.
German investigators subsequently interviewed witnesses, seeking to determine whether Hoenmanns and Reinberger should be prosecuted for what at one point was thought to be treason. The witnesses said that Hoenmanns was in a great hurry when he and his passenger climbed into the Taifun at about midday. They claimed he had failed to follow his normal practice of requesting a weather check, and had jumped down from the plane to fetch a map he had forgotten.
By all accounts he was somewhat flustered, and it is possible that this might have distracted him from his map reading and navigation when he finally took off, leading him to fly off course. All went well during the flight until he reached Cologne’s industrial area, where things began to go badly wrong. It was so foggy that he could not see the Essen to Cologne main road, which normally helped him navigate. Consequently, he turned west, hoping to skirt around the fog before turning south again toward Cologne. As he flew, he peered out of the cockpit trying to spot the Rhine, a landmark that in normal conditions would have prompted him to turn south. However, as he might have anticipated had he not been so preoccupied, the river was frozen and covered with snow, and therefore hard to differentiate from the surrounding countryside.
Unable to see the Rhine, he flew over it and ended up in Belgian airspace. His distracted mental state might also have been a factor once he realized he was lost. Perhaps he would not have flown so far west if he had been more alert, and if that had been the case, he might not have inadvertently moved the lever shutting off the petrol supply—if that is indeed what happened—thereby stalling the plane’s engine.
Hoenmanns only discovered that Reinberger was carrying secret documents when, after they had landed, they asked a farmer where they were. When the man replied that they were in Belgium, Reinberger turned white as a sheet. Borrowing matches from the farmer, a pipe smoker, he rushed back to the plane after exclaiming that he had secret documents that must be destroyed immediately. Hoenmanns moved away from the plane, acting as a decoy.
While Reinberger struggled to burn the documents behind a hedge, however, Belgian soldiers arrived. Seeing smoke coming from where Reinberger was hiding, they rushed over to investigate and seized him before he could destroy all the papers. They also captured Hoenmanns.
The drama reached its climax in the Belgian soldiers’ watch house near the bridge at Mechelen-sur-Meuse, where the two men were taken. The Belgian soldiers had unwisely left the remains of the documents lying on a table, where Reinberger and Hoenmanns could see them. With whispers and signals, the captured Germans hatched a plan that they hoped would give Reinberger a second chance to burn them.
Hoenmanns would go to the other side of the room and ask to be escorted to the washroom. While the guards were attending to him, Reinberger was to seize the documents and stuff them into the lit stove. Their plan ignored the fact that the lid on the stove was very hot. After Hoenmanns had carried out his part of the scheme, Reinberger picked up the lid and stuffed the documents into the stove. When the lid burned his hands, he dropped it, thereby alerting the guards.
The officer in charge rushed up to Reinberger, pushed him out of the way, then plunged his hands into the stove and scooped out the smoldering but still undestroyed documents. They were then locked away in another room.
Regardless of his ultimate goals, it is hard not to feel sorry for Reinberger. According to Hoenmanns’ account, his companion began to sob, and banged his head against a nearby cupboard, evidently believing that enough of the documents remained to reveal that Belgium was about to be attacked.
The repercussions could be unpleasant to say the least. There would be an international outcry. The Allies might come to Belgium’s aid—or even invade Germany. Hermann Göring and Hitler would be told how Reinberger had endangered his country’s security by taking secret documents on an airplane. Heaven help him if Hitler’s henchmen ever got hold of him!
Realizing the hopelessness of his situation, Reinberger asked the Belgian officer for his gun, saying: “I’m finished. I want to put an end to this affair right now.” The officer naturally refused to comply, even after Hoenmanns intervened, saying: “You can’t blame him. He’s a regular officer. He’s finished now.” Undaunted, Reinberger attempted to take the gun by force. The Belgian roughly pushed him back into his chair, where he collapsed and once more began to sob.
“Not realizing how important the documents were, I thought he was overdoing it a bit, and was not behaving like a man,” Hoenmanns commented later. He then described how, with a relatively clear conscience, he ate the meal he was given while Reinberger wept beside him.
Interestingly, both the Germans and the Belgians thought that Reinberger and Hoenmanns were trying to deceive them about the documents. The Germans feared that the two men were traitors, and were intentionally handing the highly secret plans to the enemy. An investigator was dispatched to interrogate Hoenmanns’ wife, Annie, and to search their Cologne apartment. Mrs. Hoenmanns told the investigator that if her husband had intended to betray Germany, she would have known about it. However, when she added that she and her husband kept no secrets from each other and were not having any marital problems, it became clear that she was an unreliable witness.
The Belgians feared that the German aviators were using bogus papers to provoke them into calling in the British and French, thereby giving the Germans a pretext to invade Belgium. However, after they had reviewed all the evidence, particularly the near-fatal crash landing, the Belgians concluded that it was unlikely that the crash had been premeditated.
That tempted them to stage a hoax of their own. They decided to trick Reinberger into believing that the most important sections of the plans had been destroyed, and then give him the opportunity to pass this on to the German authorities.
In the first part of the deception, the Belgian investigators asked Reinberger what was in the plans, and informed him that he would be treated as a spy if he did not tell them. “From the way this question was asked, I realized he [the interrogator] could not have understood anything from the fragments of the documents he had seen,” Reinberger testified later.
The second part of the stratagem involved permitting the German air and army attachés, Lieutenant General Ralph Wenninger and Lieutenant Colonel Friedrich-Carl Rabe von Pappenheim, to see the majors while secretly recording their conversation. The recording equipment was not in place at the Brussels police station, where the interview was to take place, until January 12. Only then could the meeting be sanctioned.
The report describing what was overheard during the meeting is still in the Belgian archives. It contains the following disclaimer from the man responsible for doing the recording: “I cannot claim to have heard everything because the five people often formed two groups of conversation that I could not follow simultaneously. But I have certainly recorded most of what was said.”
The meeting began with innocuous questions that had no bearing on international relations with Germany. For example, Reinberger was asked whether he needed a toothbrush. The important questions were asked only after the Belgian major, who was supervising the interview, left the room. As soon as the Germans were alone, Wenninger told Reinberger: “The day before yesterday I went to the General Headquarters who sent me here to speak to you. According to the press, you managed to burn the papers. Is that correct?”
Reinberger replied, “Yes, Herr General.”
At that point the Belgian major returned, only to leave again when asked whether Hoenmanns and Reinberger might be isolated from other prisoners. While he was absent, Reinberger told the attachés the full story: how Hoenmanns lost his way in the fog, how they had mistaken the Meuse for the Rhine, how they had had to make an emergency landing, how they had borrowed matches from the Belgian farmer on the pretext they needed to smoke a cigarette, how they had burned the documents, and how a soldier had taken a few charred pieces from the fire. It was this account that convinced the Belgian investigators who subsequently analyzed the transcript that the captured plans were genuine.
When Reinberger had finished, Hoenmanns mentioned the two matters that were worrying him. He wanted to know what Göring had said about the accident, and asked whether he could give Wenninger a letter for his mistress in Münster, to avoid a marital drama. Later Hoenmanns wrote asking the German authorities to remove any objects belonging to his mistress from the room near Loddenheide where he had been living so that his wife would not find out about his affair when his personal effects were delivered to the family home in Cologne.
Hoenmanns’ complicated domestic arrangements were evidently the least concern of the attachés and the German generals waiting to hear what Wenninger and Pappenheim had discovered. The generals of the German high command were horrified by what had happened to their attack plan. On the day of the attachés’ first meeting with Reinberger and Hoenmanns, General Alfred Jodl, the Wehrmacht’s chief of operations, gave Hitler his grim assessment of what the Belgians might have learned from it. A note in Jodl’s diary for January 12 summed up what he had said: “If the enemy is in possession of all the files, situation catastrophic!”
The German generals’ reaction to the misadventures of the two majors was generally hostile. They believed that if Hoenmanns was not a traitor he was certainly a reckless adventurer who, by his disobedience, had endangered the lives of thousands of German soldiers about to go into battle. Not surprisingly, whether by mistake or by design, the Germans ignored his instructions about his personal effects. His wife was handed a pile of letters from his mistress along with the rest of his possessions.
The Belgian government’s deception was more successful, at least in the short term. After the meeting at the police station, His Excellency Vicco von Bülow-Schwante, Germany’s ambassador in Belgium, telegraphed his superiors: “Major Reinberger has confirmed that he burned the documents except for some pieces which are the size of the palm of his hand. Reinberger confirms that most of the documents which could not be destroyed appear to be unimportant.”
This convinced General Jodl. His diary for January 13 included the entry: “Report on conversation of Luftwaffe Attaché with the two airmen who made the forced landing. Result: dispatch case burned for certain.”
There was another reason why the Belgians eventually concluded that the attack plan was genuine. On January 13, a message from Colonel Georges Goethals, Belgium’s military attaché in Berlin, but based on information provided by an informant who was in touch with Dutch military attaché Major Gijsbertus Sas, included the following words: “Were there tactical documents or references to them on Malines [sic] plane? A sincere informer, whose intelligence may be suspect, claims that this plane was carrying plans from Berlin to Cologne in relation to the attack on the West. Because these plans have fallen into Belgian hands, the attack will happen tomorrow before counter-measures can be taken.”
General Raoul Van Overstraeten, military adviser to Belgium’s King Leopold, was astonished that the informant seemed to know about the capture of the plan. It had not been mentioned in any press reports describing the crash. It was possible that the informant’s tipoff was part of the same German hoax, but it also might be genuine. Acting on the assumption that it should be taken seriously, Van Overstraeten altered the warning that the Belgian chief of the general staff, Lieutenant General Edouard Van den Bergen, had drafted to send to all Belgian army commanders on January 13. Instead of stating that an attack on the next morning was “probable,” it now stated that the attack was “quasi-certain.”
Van Overstraeten’s act was controversial. Some of his Dutch counterparts were less impressed by the intelligence emanating from their attaché’s informant. Sas had told the Dutch armed forces commander in chief, General Izaak Reynders, that he was receiving his intelligence from a man in the German Abwehr (military intelligence), but he refused to name his source. That the man worked in the Abwehr bothered Reynders. The Abwehr’s job was to deceive the enemy, so how could they be sure that the Sas source was not attempting to deceive them?
Van Overstraeten’s change, made without consulting Van den Bergen, left the Belgian chief of the general staff with a difficult dilemma. That night, a popular current-affairs program was about to be broadcast on Belgian radio, and Van den Bergen realized that if he moved quickly he could ask for an announcement to be made that all eighty thousand Belgian soldiers on leave should return immediately to their units. This would enable many to be in the front lines before dawn, when any attack by the Germans was likely to commence.
Without discussing the broadcast with Van Overstraeten or King Leopold, and without knowing about the decision that had been reached earlier that day to keep the Germans in the dark as to whether or not Belgium had their attack plans, Van den Bergen authorized the announcement. Two hours later, he made another dramatic gesture, once again without obtaining the agreement of Van Overstraeten or the king. Realizing that the freezing weather conditions would make it difficult to quickly move aside all the barriers that had been erected on the country’s southwestern border with France, he ordered them removed immediately. The idea was that at least some would be out of the way before the Germans attacked, thereby enabling British and French troops to march into Belgium as soon as they were summoned.
If the Germans had attacked on the morning of January 14, Van den Bergen would probably have been congratulated for his quick thinking. However, because they did not attack then, or three days later (Hitler had called off the attack scheduled for January 17 because of the weather), Van den Bergen was in disgrace for acting without the permission of King Leopold, his commander in chief. Van Overstraeten rebuked Van den Bergen so harshly that the Belgian chief of staff’s reputation never recovered. He was forced to resign at the end of January.
One of Van Overstraeten’s chief complaints was that Van den Bergen had given the Germans grounds for believing that the Belgians had their plans. The Belgian government’s desire to keep the possession of the plans a secret was, however, to be further undermined by a second attempt to protect the country. This time King Leopold was to blame.
On the morning of January 14, he had sent a message to Winston Churchill, then first lord of the Admiralty, via Admiral Sir Roger Keyes, asking for certain guarantees. Keyes, referred to by the Belgians as “Mr. X,” had established himself as the secret link between the British government and the king. The requested guarantees included assurances that the Allies would not open negotiations for any conflict settlement without Belgium’s agreement.
Keyes added a rider stating that he believed Leopold might be able to persuade his government to call in the Allies immediately if the guarantees were forthcoming. This was of interest to the Allies because, ever since war had been declared, both Britain and France had been trying to persuade Belgium to allow them to move in.
There is no transcript of Keyes’ conversation with Churchill, but if Keyes really did accurately state what he meant to say, his message, like Chinese whispers, was altered the farther down the line it went. By the time it reached the French later that afternoon, there was no reference to the fact that Keyes was only giving his opinion about the offer to call in the Allies. The French record of what was on offer stated that “the King would ask his government to invite the Allied armies to occupy defensive positions inside Belgium immediately” if the Belgians received satisfaction in relation to their requested guarantees. Edouard Daladier, the French président du conseil in January 1940, quickly told the British government that, as far as France was concerned, the guarantees could be given.
The upshot was that the French believed the Belgians would receive a satisfactory response from the British government in relation to the guarantees, and would then immediately invite the Allied armies to march in. With that in mind, during the night of January 14-15, General Maurice Gamelin, the French army commander, ordered the Allied troops under his control to move up to the Franco-Belgian border so that they would be ready to enter at a moment’s notice.
The French told the Belgians of this maneuver during the night. It was only at 8 A.M. on January 15 that Gamelin saw the British response to the request for guarantees: They were offering a watered-down version that would most likely be unacceptable to Belgium. Three hours later Daladier, prompted by a desperate Gamelin, told Pol Le Tellier, Belgium’s ambassador in Paris, that unless the French had an invitation to enter Belgium by 8 P.M. that night, they would not only withdraw all British and French troops from the border but would refuse to carry out similar maneuvers during future alerts until after the Germans had invaded.
The rising tension between France and Belgium is underlined by France’s decision to install a tap on the telephone line that connected the Belgian Embassy in Paris with Belgium, an extreme step given that the two countries were allies in everything but name. A transcript reveals what was said when the Belgian foreign minister, Paul-Henri Spaak, spoke to Le Tellier at 5:20 P.M. on January 15—just two hours and forty minutes before the French deadline expired. The French telephone tapper, who identified Spaak as speaker “X” in the transcript, noted that “Minister X appears to be in a very bad temper.” The conversation ran as follows:
X: “I will keep you informed.”
Le Tellier: “But the big chief is waiting for my reply.”
X: “Are they able to concentrate their troops in one night?”
Le Tellier: “Yes, but if the enemy sees or hears about the concentration!”
X: “Believe me, I will do my best.”
Le Tellier: “I don’t want to be rude, but will I have some news from you tonight?”
X: “I cannot take this kind of decision in one and a half hours. If they cannot, or will not, wait for our reply, they must act as they see fit. In any case, I’m going to deal with the problem. I’m doing nothing else at the moment, but I don’t know if I’ll have a reply before 8 P.M.”
At 8.05 P.M. the telephone tapper heard Spaak giving Le Tellier the Belgian government’s response:
X: “It’s very simple. We cannot reply in the affirmative. A long note will be sent tomorrow. It’s absolutely impossible.”
Le Tellier: “Will they have to take steps as a result of this reply? They are in the open and concentrated.”
X: “There’s nothing stopping them.”
Le Tellier: “But they are concentrated.”
X: “What do you want me to do? I know the situation, but they are speaking of different dates. It could be tomorrow, or the 17th or the 20th. This problem you are talking about is a technical matter. If they cannot remain where they are, it’s just too bad. Let them decide what to do. Don’t repeat that. Tell them simply that I cannot reply in the affirmative. I am adding, for your ears only, from all points of view, it’s impossible.”
Le Tellier: “Must they remove their troops from the frontier?”
X: “If they have to remove them all, then they must go ahead and do that. I’ve no problem about that. They have not understood all the political consequences it would cause. What they’ve asked is extraordinary.”
Le Tellier: “Understood. I’ll pass on what you said just now, and nothing else, and I’ll call you back with their reaction.”
Apart from some bitter recriminations, there was nothing more that Daladier and Gamelin could do to coax the Belgians into letting the Allied armies into Belgium. They were forced to order the British and French troops back to their original positions.
In the short term, no harm seemed to have been done. But in the long term, the maneuver was disastrous. The Belgians felt obliged to tell the Germans they had the attack plan. When Joachim von Ribbentrop, Germany’s foreign minister, retorted that it was out of date, he was being more truthful than he intended.
The entry in General Jodl’s diary for February 13, 1940, reveals the fundamental change to the plan that had been made after Reinberger and Hoenmanns’ accident. Instead of being committed to the attack detailed in the captured documents, whose principal thrust was on Belgium’s northeastern frontier, Jodl recorded that Hitler wanted the German panzer divisions concentrated farther south. “We should let them attack in the direction of Sedan,” Hitler told Jodl. “The enemy is not expecting us to attack there. The documents held by the Luftwaffe officers who crash landed have convinced the enemy that we only intend to take over the Dutch and Belgian channel coasts.”
Within days of this discussion, Hitler had talked to General Erich von Manstein, the former chief of staff of German Army Group A, who for some time had been championing this new plan, and the Führer had given it the green light. The plan that had caused so much mayhem when the Belgians captured it in January 1940 was to be quietly shelved.
The adoption by the Germans of the revised Plan Yellow (Fall Gelb), while the Allies were still expecting Hitler to go ahead with the captured version, meant that the Germans could set a trap. An attack would still be made on Belgium’s northeastern frontier, but as one writer vividly described it, it would merely be “the matador’s cloak,” tempting the Allied armies to move as many troops as possible into Belgium, thereby carrying out in full the plan that had been aborted on January 14-15. Once the Allied “bull” was safely in Belgium, the main German thrust—backed by most of the panzer divisions—would pass through the Ardennes, cross the Meuse between Sedan and the area north of Dinant, then cut across France to the coast, thereby isolating and surrounding the armies in Belgium, separating them from their supplies and forcing them to surrender.
Clever as this ruse was, it would only work if Gamelin stuck to his original strategy. That was asking a lot, given that until January 14, 1940, his intuition had been impeccable. Had he not correctly guessed the content of the German generals’ original Plan Yellow?
Nevertheless, after the capture of the German plan, everything had changed. It did not take a genius to conclude that the Germans might devise a new plan now that the Allies had seen the original version. But for some inexplicable reason, Gamelin failed to adapt his strategy to take into account the new circumstances. In their turn, Lord John Gort, commander of the British Expeditionary Force in France and Belgium, and the British government failed to point this out.
Perhaps notwithstanding the Belgian verdict on the captured documents, British generals and politicians, like the British ambassador in Brussels, still believed they were a German “plant.” Or perhaps they were so embarrassed by the small contribution Britain was making to the coming ground war that they did not feel entitled to question French strategy.
Whatever the reason, by blindly obeying French orders, they failed to appreciate that the Allied defensive plan, requiring them to charge into Belgium as soon as the Germans invaded, represented a disaster waiting to happen.
Originally published in the Spring 2008 issue of Military History Quarterly. To subscribe, click here.