Cracking the German Dams

VOLUME 172

NUMBER 6

DECEMBER, 1943

86th YEAR OF CONTINUOUS PUBLICATION

by WING COMMANDER GUY P. GIBSON

THE flak over France wasn’t bad. It was coming up all around in spasmodic flashes as some straggler got off his course and struggled through a defended area. Otherwise the night was lovely. There was a three-quarter moon which shone brightly into my Lancaster, lighting the cockpit up almost as if it were day. Down below us, the gray features of France were partially hidden by a thin layer of white cloud.

It was getting hot inside. I yelled to my wireless operator, “Hello, Hutch. Turn off the heat.”

He said, “Thank God for that.”

The heat in a Lancaster comes out somewhere round the wireless operator’s backside; hence the obvious relief expressed by the long-suffering Hutch.

All around me, above, below, and on every quarter, I could see the Lancasters moving forward towards their target, flying straight and flying fast, flying with their great chins thrust forward and looking to me more purposeful than anything I had ever seen before.

I was feeling pleased because this was going to be my last raid before going on a few days’ leave; for now I had done 173 sorties without having had much rest. It was almost too good to be true that after this raid on Stuttgart I should be able to go down to Cornwall with my wife and have the time of my life. Once again I should be able to walk down to St. Ives with my pipe in my mouth and my dog running along by my side. Once again I should be able to stand and watch the sea when it became angry and fought with the northeast wind; then in the evenings, instead of sitting up here with an oxygen mask over my face, I should be leaning back in my armchair looking at the ceiling and scratching the back of my dog. There would be no bomber raids to organize, no bomb loads to think about.

As I was thinking these things, my flight engineer yelled, “ Fort outboard’s going, sir!”

Sure enough, t he port outboard engine was packing up. I could feel it in the throttle control. There was no power coming from this engine. Rapidly, my heavily laden Lancaster had to lose height.

This was bad. If I turned back now I should have to go out again tomorrow night. Maybe there would be no tomorrow night. Maybe the weather would be bad. Maybe I should have to wait four days; I should have to wait four days for my leave. Maybe it would be better to go on.

Seriv, my navigator, was standing at his station scratching his head and watching the air-speed needle drop rapidly.

I said, “What shall we do, Scriv?”

Copyright 1943, by The Atlantic Monthly Company, Boston, Mass. All rights reserved.

“It’s up to you, sir.”

“ O.K., Scriv, we are going on at low altitude. We will try to climb up to bomb when we get there.”

The Lancaster slid quietly out of formation and, like a wounded bird, dropped towards the earth. On all sides of me the flak was coming up from Mannheim, Frankfort, and Mainz. From where I was, I had a grandstand view of the boys up above getting shot at. But the Huns did not shoot at me. They did not even fire machine guns at me. Perhaps they thought that I was a night fighter. Now and again I caught sight of a Lancaster far above, four miles above, as it got into the beam of a searchlight and as a light flashed on its wings; and almost I thought I could distinguish the separate aircraft as they flew over, merely from the light of the flames which danced through the streets of Stuttgart. The town was on fire.

An 8000-pounder came whistling past my wing tip on its way down, and a few seconds later a great slow, heavy flash came up from the ground where it had landed and my aircraft was bounced and tossed about as though it were a leaf. I remember that once I distinctly saw a shower of incendiaries not 200 yards in front of me. It is indeed curious to be underneath a heavy bombing raid in an aeroplane.

We dropped our load, and my poor Lancaster on its three engines jumped into the air as the bombs fell out of its belly and I banked around and dived for the deck.

During these moments there had been little talk, but once we were clear of the target area all the boys on board started talking.

“Leave tomorrow.”

“Tomorrow we go on leave.”

“ I’m going fishing.”

“I’m going to sleep.”

“Tomorrow we go on leave.”

My wife had been sweating it out in a factory near London for a long time without any rest and now I should be able to take her home and let her breathe for a moment the fresh and pleasant air of Cornwall.

Soon, after dodging the night fighters, we were back over England, and a few minutes later I was in my room, hurriedly packing my clothes before jumping into bed. As I dozed off, I thought of the morrow and of leave, and of the sound of the waves on the rocks down in Cornwall.

2

REPORT to C. in C. immediately.” It was early when I was waked up and given this message. I used some strong language — stronger language even than I use sometimes when we are on a raid — and I wondered what was going to happen to my precious leave. For a moment I thought that perhaps this business could wait, but then almost at once I knew that it couldn’t, for the C. in C. is the C. in C., and I was only a Wing Commander. I rang up the flights and told them to start up my communications aircraft, and in a few minutes I had dressed and was away.

The Air Marshal was very nice to me, and as I went into his room he said, “Hello, Gibson. Sit down.” Then he told me quietly that I wasn’t going to have any leave. He told me that I was to form a new squadron, a special squadron picked out of the best crews in the Bomber Command, the squadron which would have to undertake a most important mission. He told me that if this mission was successful, we should have succeeded in dealing to Germany in one night the most damaging blow of the war.

He offered me a Chesterfield and said, “I know that you are due for some leave and I know that you are due for a rest, but I should like you to do one more raid.” Then he began to talk, and although I cannot remember exactly what he said, I know that when he had finished I was already out of my chair and ready to start work.

He spoke to me about the Möhne Dam and about the Eder Dam. He spoke to me for a long time and told me of their importance and of the difficulty which we should have in destroying them.

It took me an hour to pick my squadron. I wrote the names down on a piece of paper and gave them to a man with a red mustache who was sitting behind a huge desk. Then I got in touch with my wife and told her that our leave was postponed because I had one or two things to do before I could get away.

The next night I arrived in the mess at Dersingham with my batman and my dog trotting happily along at my heels. And there I met the boys. I knew them all. I had picked them myself because I honestly believed from my own personal knowledge of them that they were the best bomber crews in the RAF. I knew that each one of them had already done his full tour of duty and should really now be having a well-earned rest; and I knew also that there was nothing that any of them would want less than this rest when they heard that there was an exciting operation on hand. There was Mickey Martin from Australia, who had done 48 trips. There was Dingy Young from America, who had done 65 trips. There were Dave Shannon, Les Munroe, Joe McCarthy, John Hopgood, and many others — all in all, they probably knew more about the art of bombing than any other squadron in the world.

Next morning I got them all together. There were 25 crews, which means 175 men — pilots, navigators, wireless operators, bomb aimers, engineers, and gunners, and every one of them an old hand at the game.

My speech to them was short. I said: “You’re here to do a special job. You’re here as a crack squadron. You’re here to carry out a raid on Germany which will ha ve tremendous results. What the target is, I cannot tell you, nor can I tell you where it is. All I can tell you is you will have to practice low flying all day and all night until you know how to do it with your eyes shut.

“I needn’t tell you that we are going to be talked about. It’s very unusual to have such a crack crowd of boys in one squadron. There are going to be a lot of rumors. You’ve got to stop these rumors. You’ve got to say nothing. When you go into the pubs at night you’ve got to keep your mouths shut. When the other boys ask you what you are doing, just tell them to mind their own business — because, of all things in this game, security is the greatest factor.”

I said a lot more, but I have forgotten what it was; but it was all to the same point. And then I handed over to Dingy Young, my second in command, and told him to get on with the low-level training.

The security measures which were taken were far-reaching and efficient. All our telephone wires were tapped, guards were stationed all around the vicinity, frequent lectures on security were given to every man on the station, and the barmaid in the local pub was given three months’ holiday.

3

THEN I went down to London, and there I met a man of whom I shall say very little. He was as much responsible for the success of this operation as all the pilots and air crews put together. He is one of the real backroom boys of whom little can be told until after the war, and even then I am not sure that you will hear a great deal of their story.

We met together in a small, dark office. He pulled out a drawing and gave me a short lecture on the science of damology — which is, of course, the science of breaking down dams.

He said: “Now you may think me a stupid old man, but wait until I tell you what I know about the Möhne Dam. It is a military objective which I have been studying ever since the war began.

This dam” — and he pulled out some pictures — “is some 850 yards long, 150 feet thick, and it is as high as it is thick. You can imagine that many attempts have been made,” he went on, “to try to evolve some method of breaking down these walls, but it is not so easy as it looks. When you consider that we in London here think ourselves safe from an ordinary explosive bomb when we are behind three feet of concrete, you will begin to realize what I mean when I talk about shifting 150 feet of the stuff.”

I said, yes, I thought I did.

He went on: “We have been making experiments and trying out the effect of explosives on such walls for some time. Now let me explain.” He opened a book and showed me pictures of a small dam, some six feet across, which had been breached by a certain charge of explosive. He said: “Our next experiment is to try out our theories on a larger dam. We have built down in the South a dam some 200 feet across. This dam, I might tell you, is brick for brick the same as the Mohne Dam. The lake is full of water and we intend to go down at once and try out there the theories that we have evolved with the smaller models.”

This, I thought, was going to be fun. I could remember the time when I was a kid, when we used to go down to the beaches in Cornwall and shovel the sand across the little streams which ran down from the granite cliffs. I could remember how we dammed up the water until it made a big pool behind the sand, and I could remember how, when it was time to go home for supper, I used to smash the whole thing with one sweep of my spade, letting the water rush out down the beach. I could also remember how angry my brother used to get when I did this.

I said to the scientist, “I can see that this last experiment of yours will give us roughly what we need. Let me know the results.”

A few days later he rang up and told me that the experiment had proved a success. “But we are not finished,” he added; “we are not nearly finished.”

At that time a certain county council in the Midlands of England had just built a new dam to supply their town with water. We heard about it and wrote to them and asked them if we could knock down their old dam so that the water would run into their newly built one. They replied that this was fine because they wanted to knock it down anyway, and so the scientist and I went to work.

There followed a series of dramatic experiments. On one cold winter morning after another I flew over this dam and dropped my missile, and always as I did so, this great man, the scientist, was standing on the edge of the lake with his shoulders hunched and his hands in the pockets of his overcoat, watching to see what would happen. One after another, our experiments failed. I can remember clearly the sight of that small, cold figure standing alone on the brink of the water, standing and looking up at my Lancaster. There was a tenseness about the way in which he stood, with his legs apart and his chin thrust out, and there was a fearful frightening expectancy about everything; there was snow on the ground, which made things sharp and bright and real.

For many days this man worked and I flew. He modified and experimented, and I watched and watched. Then suddenly one morning in April, on one of the first days of spring, I flew over and dropped one which worked. The man on the ground danced and waved his hands in the air. I could see him from my cockpit as I banked around after my run, and I waved back at him and shouted into the noise of the engines; and I believe that the man on the ground threw his hat into the air, for that was a wonderful moment.

Then there were urgent telephone calls, and many signals written in cipher, and messengers rushing to and fro, and factories received priority orders so that men and women worked throughout the day and the night making these things which we were to carry with us over to Germany to be dropped in the Möhne Lake.

4

AFTEK all that, I took myself back to my squadron. By now the boys had made themselves very proficient in flying at low level around the countryside, and they found that navigation in itself was no longer a problem. We therefore turned ourselves to practicing a special form of attack, which we should have to make on the dam walls. Night after night, day after day, we went flying up and down lakes in Scotland, in the Midlands, and in Wales, practicing this very special form of attack. One of our hardest problems, we found, was to fly at 45 feet above the water; to fly at exactly 45 feet, not 44 feet or 46 feet, but 45 feet. It is a very difficult thing for a pilot to judge his height above calm water, and many a flying boat has crashed as a result.

Such was our problem, for while it was comparatively easy to get the air speed and although it was easy to get the sighting line just right, we could never be sure that we were exactly at the right height. Perhaps I ought to tell you here that it was obvious that our missiles would have to be dropped with extreme accuracy within literally a matter of feet of a certain spot. And it was necessary also to fly fast; otherwise the operation became too hazardous to allow for the possibility of success.

All these things we could do except the business of maintaining an exact height. But this difficulty was ultimately overcome in a most simple manner and, although I should like to tell you how it was done, I think that the Germans would like to know even better. The method we used was accurate to a few inches. It made us extremely vulnerable to flak fire, but this risk had to be taken.

After two months of continuous hard training, involving at least 150 hours of flying for each person, I considered that my squadron was fit to undertake the operation.

At the same time we had reconnaissance aircraft flying out over Germany watching these dams as a cat watches a mouse. They were looking for two things. The first, and the more important, was the density of the defenses and whether they were being increased. The second was the height of the water level. You see, a dam can best be attacked when there is a great quantity of water in the dam itself, for there is then a greater mass which will exert greater pressure against the wall.

It was very thrilling in those cool spring evenings to watch the water level rise. By April 15 it was some 15 feet from the top of the dam wall. By the beginning of May it was only 10 feet. By May 10 the water level was almost right for the attack.

On this date we carried out a full dress rehearsal against a dam in Wales. The whole thing was a failure.

The trouble was intercommunication. On attacks of this sort it is absolutely necessary to have speaking telephony between all the aircraft. We didn’t have any. And when we got back I told the Commander in Chief that unless we were equipped with radio telephony such as fighters use, the whole mission would be a failure. Within a few hours the whole squadron was equipped with the very best and most efficient telephony sets in the whole of the Royal Air Force.

Next night we carried out another dress rehearsal and it was a success.

By now it was obvious that we should have to carry out the raid within the next few days. The weather was good, the moon was full, and we were ready.

On May 16, reconnaissance aircraft reported that the water level was just right for the attack. It was a great moment when the public address system on the station said: “All crews of No. 617 Squadron report to the Briefing Room immediately.”

The boys came in hushed, having waited two and a half months to hear what it was that they were going to attack. There were about 175 young men in that room, rather tousled and a little scuffy and perhaps a little old-looking in spite of their youth. But they were experts, beautifully trained, and each one of them knew his job as well as any man had ever known any job which he was to do. I let the scientist tell them all about it.

In his gentle, benign way he repeated almost exactly the things which he had told me two and a half months before. He told them how the dam had been built and of what it was made. He told them how thick it was and how difficult it would be to crack, and he told them of the principle upon which we were going to work. Then he told them that it would not be easy, and everyone understood what he was trying to say.

Then I got up and explained the type of attack which we were to use, although by now they knew it backwards because they had practiced it so much.

Naturally a lot of special preparation had to be made. Special ammunition was fitted to the guns. Special armor plating was fitted to the aircraft. But all this had been prepared beforehand and the whole thing ran like clockwork.

Standing around an hour and a half before the take-off, everyone was tense and no one said very much. The long practice and the waiting and the business of being kept in the dark had keyed them up to a point where one could feel that it would be better if they had stood on their toes and danced and shouted out loud. But they stood there with their hands in their pockets, smoking cigarettes and saying little.

I said to Hoppy, — Hoppy who had been with me a year and a half, who had flown in 40 raids with my squadron, — “Hoppy, tonight’s the night. Tomorrow we will get drunk.” I did not know then that I should never see Hoppy again.

Soon it was time to take off, and we rumbled out onto the flare path in one great formation, and soon all nineteen of us were en route to Germany at zero altitude.

It was a wonderful sight. There was a full moon, and on either side of me stretched the two long arms of Lancasters forming a V, flying in perfect formation, each man knowing the plan, each one knowing his job.

Soon, low and squat on the horizon, appeared the Dutch coast, unfriendly and evil, a long, flat, bleak expanse squirting up flak in many directions. But there were ways and means of getting through that barrage, and we knew all about that. Like a ship threading its way through a mine field, we skirted around defenses and flew on towards the heart of Germany. We were flying low. We were flying so low that more than once I had to pull the stick back quickly in order to hop over a high-tension wire or a tall tree.

We didn’t all get through. One aircraft had already hit the sea, bounced up, lost both its outboard engines and flown back on the inboard two. Two other aircraft were hit by light flak a little later on, and I had to order them to return to base. I imagined the feelings of the crews of these aircraft, who, after many weeks of intense practice and looking forward to this thing, now at the last moment had merely to hobble home and land with nothing accomplished. I felt very sorry for them.

That left 16 aircraft going on; 112 men,

5

THE journey into the Ruhr Valley was not without excitement. They did not like our coming. And they knew we were coming. We were the only aircraft operating that night, and down in their deep plotting rooms the Huns stayed awake to watch us as we moved steadily on.

When we crossed the Rhine there were barges on the river equipped with quick-firing guns and they shot at us as we flew over, but we pressed on towards the Ruhr. Time and again searchlights would pick us up, but we were flying very low, and although it may sound foolish and untrue when I say so, we avoided a great number of them by dodging behind the trees.

One of the pilots, a grand Englishman from Buckinghamshire, was unlucky. He was flying on my right. He got blinded in a searchlight and his aircraft reared up like a stricken horse and plunged into the deck and burst into flames.

We fought our way past Hamm, the well-known Hamm which used to be bombed so many times, and then as we came over the hill we saw the Möhne Lake. And then we saw the dam itself, and in the early light of the morning it looked squat and heavy and unconquerable. A structure like a battleship was shooting up flak all along its length. It was light flak mostly, green, yellow, and red, and the colors of the tracer reflected upon the face of the water in the lake; it reflected upon the dead calm of black water, so that it seemed to us that there was twice as much as there really was.

I spoke to my squadron: “O.K., chaps. Come in to attack when I tell you. I’ll attack first.”

Then I began my approach. As we came in over the tall fir trees, Spam, my Australian bomb aimer, said, “You’re going to hit them. You’re going to hit these trees.”

“That’s all right, Spam. I’m just getting my height.”

I was looking at the special sight on my windshield. Spam had his eyes glued to the bombsight in front, his hand on the button. The bomb doors were open. Terry, the navigator, was checking the height. The flight engineer was keeping the speed constant.

The gunners saw us coming. It was not exactly an inferno. I have been through far worse flak fire than that; but we wore very low. There was something sinister and slightly unnerving about the whole operation.

My aircraft was so small and the dam was so large; it was so thick and solid, and now it was angry. My aircraft was very small.

We skimmed along the surface of the lake, and as we went my gunner was firing into the defenses, and the defenses saw us coming and fired back. Their shells whistled past us but for some reason we were not being hit. Spam said, “Left . . . little more left . . . steady . . . steady . . . steady . . . bombs gone!”

Then it was all over.

Trevor, the rear gunner, said, “I’ll get those devils.” And he began to spray the dam with bullets until at last we were out of range.

As we circled round I saw that we had not broken the dam, and so far as I could see there was not much damage, but the explosion of my mines had caused a great disturbance upon the surface of the lake and the water had become broken and furious, as though it were being lashed by a gale. I had to wait for this to calm down and it took quite a long time.

“Hello, M Mother. Hello, M Mother. You may attack now. Good luck.”

Hoppy began his attack. Hoppy the Englishman, casual, keen now only on one thing, which was war. I saw him approach. I saw him drop his mines. I saw him shot down.

Many minutes later I told No. 3 to attack. He was all right; he got through. It was then that I saw that the dam wall had moved. It had moved back on its axis and I knew then that if we could only go on pushing, in the end it must collapse. Then one after the other, No. 4, No. 5, and No. 6 went in to attack. Each one of them dropped his missiles exactly in the right place. I was flying up and down watching them. My rear gunner was all the time shooting at the defenses and trying to take some of the flak away from those who were attacking.

Now we had been over the dam for more than an hour, and all the while I was in contact with my aerodrome at home. I was in contact with my Commander in Chief and with the scientist, the man who was witnessing the last great experiment in the science of damology. I am told that he sat in the Operations Room with his head in his hands, listening to my report as one by one I announced that aircraft had attacked but that the wall had not broken.

But I knew that the structure was shifting and then suddenly, as the last aircraft attacked and as I watched the mines drop in exactly the right place, a great column of whiteness rose up a thousand feet into the air and the dam wall collapsed. I saw it go, but I could not believe that it had happened. I heard someone shout, “I think she’s gone! I think she’s gone!” And other voices picked up the call and quickly I said, “Stand by until I make a recco.”

Now there was no doubt about it. There was a breach 100 yards across and the water was gushing out and rolling down into the Ruhr Valley towards the industrial centers of Germany’s Third Reich.

I passed the message home to my station, and I am told that when the news came through, there was great excitement in the Operations Room. I am told that the scientist leaped up and danced around the room and shouted the news.

Then I looked again at the dam and at the water. It was a sight such as no man will ever see again. Down in the valley we saw cars speeding along the roads in front of this great wave of water which was chasing them and going faster than they could ever hope to go. I saw their headlights burning and I saw the water overtake them one by one, and then the color of the headlights underneath the water changed from light blue to green, from green to dark purple, until quietly and rather quickly there was no longer anything except the water.

The floods raced on, carrying with them as they went viaducts, railways, bridges, and everything that stood in their path.

Then I feit a little remote and unreal sitting up there in the warm cockpit of my Lancaster, watching this mighty power which we had unleashed; and then I felt glad because I knew that this was the heart of Germany and the heart of her industries, the place which itself had unleashed so much misery upon the whole world.

It was the success of an ambition. The success of achievement, made possible by the work of ordinary boys flying ordinary aeroplanes, but boys who had guts.