When we had all got fully trained in our special form of attack we held a full-dress rehearsal which some few senior officers took an interest in. It was a complete failure. Aircraft went astray, some nearly collided, others went home browned off. The trouble was inter-communication. On attacks of this sort there must be no allowance for anything to go wrong, and things had gone wrong here. The radio-telephone sets which we were using were just not good enough. We would have to use fighter sets. When we got back I told the AOC that unless we were equipped with VHP the whole mission would be a failure. I told him that I had been asking for it for some time. He said. 'I'll fix it.' He was as good as his word. Within a few hours a party of men landed on the aerodrome and went to work. Next day the whole squadron was equipped with the very best and most efficient radio-telephonic sets in the whole of the Royal Air Force. And not only this, but my aircraft and the deputy-leader's had two sets on board, so that if one should go wrong we would have the other.

Next night we carried Out another dress rehearsal, and it was a complete success. Everything ran smoothly and there was no hitch; that is, no hitch except that six out of the twelve aircraft were very seriously damaged by the great columns of water sent up when their mines splashed in. They had been flying slightly too low. Most of the damage was around the tails of the aircraft; elevators were smashed like plywood, turrets were knocked in, fins were bent. It was a miracle some of them got home. This was one

of the many snags that the boys had to face while training. On the actual show it wouldn't matter so much because once the mines had dropped the job would be done and the next thing would be to get out of it, no matter how badly aircraft were damaged by water or anything else. But the main thing was to get the mines into the right spot.

The nature of Wallis's weapon made it necessary to attack the targets from a height of sixty feet, and this being so, even a small amount of opposition made such an operation extremely hazardous. At the time of the attack the Mohne dam was well defended, but the others were not, and it was clear that such an operation could not be repeated against similar targets if the enemy were to defend his dams at all strongly as he was now perfectly certain to do; in particular, it was extremely doubtful whether the operation could have been carried out at all if there had been searchlights on or near the dams. In any case, it was only possible to attack the dams during a short period of a week or two in any given year, when the dams were at their fullest. For these reasons no further attacks on dams were made with Wallis's weapon, though the Sorpe dam was attacked with heavy bombs at a later stage in the war; this attack also failed to breach it.

Nineteen Lancasters took off for the attack. Three had to return early, and eight were missing. The Lancasters flew at a very low level the whole way, using a very carefully planned course; it is probable that most of the musing aircraft got slightly off course and ran into gun-defended areas. This risk had to be taken since the risk from enemy fighters on a moonlight night to a small and scattered bomber force would have been even greater if they had flown above one thousand feet. There would, of course, have been a better chance of breaching the Sorpe dam or other Ruhr dams - the Schweime dam was also

attacked without effect by one aircraft on the same night - if so many aircraft had not been lost on the way to the target, and if the whole squadron had been able to attack.

The breach of the Mohne Dam released a flood of one hundred and thirty million gallons, but the destruction caused by flooding was not, and was never expected to be, as serious as the subsequent shortage of water for industrial purposes. This shortage was most serious in the eastern districts of/the Ruhr, but the enemy still had the water from other reservoirs whose dams were unbroken and from wells. The Eder dam was primarily intended not to provide water for industry but to prevent flooding of agricultural land, to make the river Weser more navigable, and to supply some of the water for the Mittelland Canal. The dam held back 202,000,000 tons of water and the release of this flooded considerable areas in Kassel. Such a disaster, brought about by only nineteen aircraft, must undoubtedly have caused great alarm and despondency in Germany.

Heavy blows of a new kind were delivered against Germany's war industry early yesterday, when a force of Lancaster bombers breached the enemy's three greatest dams at the Mohne, Eder, and Sorte reservoirs, which together control more than two-thirds of the water storage capacity of the Ruhr.

Aerial reconnaissance shows that the Mohne Dam has been breached over a length of 100 yards, that water is pouring down the Ruhr valley, that railway and road bridges have broken down, and that hydro-electrical power stations have been destroyed or damaged. The Eder, which controls the head waters of the Weser and Fulda valleys and operates several power stations, is also breached. Photographs show the river below in full flood. Floods are also rising in the Dortmund area, 30 miles away.

Picked Lancaster crews had been training in secret for the operation and only about half a dozen people in Bomber Command knew anything about it.

The dams were specially constructed to meet the enormous demands on water made by the Ruhr factories. The 134,000,000 tons controlled by the Mohne represents 30,016,000,000 gallons while the capacity of the larger Eder is 45,218,000,000. What these figures mean may be gathered from a comparison with the daily normal flow of the Thames at this time of year. At the height of the river's flow only 2,500,000,000 gallons pass down the Thames daily.

The plan for the operation was that three waves of aircraft would be employed. The first wave of nine aircraft, led by Gibson, would attack the Mohne Dam, then the Eder followed by other targets as directed by wireless from 5 Group HQ if any weapons were still available. This wave would fly in three sections of three aircraft, about ten minutes apart, led by Guy Gibson, Melvin Young and Henry Maudslay. Melvin was to fly accompanied by David Maltby and David Shannon. The second wave would fly, by a different route to confuse enemy defences, to the Sorpe Darn. Indeed, because this route was slightly longer via the islands off north Holland, the second wave actually took off before the first wave. The third wave, also of five aircraft, was to set off later and act as a mobile reserve to be used against such dams as were still unbroken. In all nineteen Type 464 aircraft and their crews were available. The crews of Divall and Wilson had sickness and one aircraft could not be repaired from damage during training.

The Operational Executive Order required that the raid be flown at low level, not above 500 feet, except between Ahlen, the final waypoint, and the target where the leader of each section should climb to 1,000 feet ten miles from the target, presumably to ensure finding the target with certainty. For reasons of surprise, it would be desirable to fly as low as possible to reduce the chance of being seen by the German radar, and thus risk interception by fighters, and to minimize the time of exposure to anti-aircraft guns (flak). The 500 feet limit was an acceptance that it would be essential to identify turning points accurately and the section leaders would have felt particular responsibility to ensure that they kept to the route, which had been devised to avoid known flak locations as far as possible. After the raid Maltby and Shannon commented that Melvin had shown a tendency to fly higher than them, and they had used Aldis signal lamps to warn him to keep low. For his part he would have been feeling a great responsibility to lead his team accurately. It may also be that, with relatively little recent flying, on his first operation in a Lancaster and his first at all for nearly a year, and with a crew with little operational experience, he was more concerned about hitting obstacles on the ground than they were - he had never seen himself as "the fighter pilot type".

The hazards of low level operations over enemy, territory were such that Harris generally disapproved of using heavy bombers in this role. Operation Chastise was an exception, but the loss on the raid of several aircraft to flak and surface impact supports Harris's general view.

The gunners had seen as coming. They could see us coming with our spotlights on for over two miles away. Now they opened up with the tracers began swirling towards us; some were even bouncing off the smooth surface of the lake. This was a horrible moment. I think at that moment the boys did not want to go. I know I did not want to go. I thought to myself, "In another minute we shall all be dead - so what?" I thought again, "This is terrible - the feeling of fear - if it is fear." By now we were a few hundred yards away, and I said quickly to Pulford, under my breath, "Better leave the throttles open now and stand by to pull me out of the seat if I get hit." As I glanced at him I thought he looked a little glum on hearing this.

The Lancaster was really moving and I began looking through the special sight on my windscreen. Spam had his eyes glued to the bombsight in front, his hand on his button; a special mechanism on board had already begun to work so that the mine would drop (we hoped) in the right spot. Terry was still checking the height. Joe and Trev began to raise their guns. The flak could sea us quite clearly now. It was not exactly inferno. I have been through far worse than that; but we were 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 thick and solid, and now it was angry. We skimmed along the surface of the lake, and as we went my gunner was firing into the defences, and the defences were firing back with vigour, their shells whistling past us. For some reason we were not being hit.

Spam said, "Left - little more left - steady - steady -steady - coming up." Of the next few seconds I remember only a series of kaleidoscopic incidents.

The chatter from Joe's front guns pushing out tracers which bounced off the left-hand flak tower.

Pulford crouching beside me.

The smell of burnt cordite.

The cold sweat underneath my oxygen mask.

The closeness of the dam wall.

Spam's exultant, "Mine gone."

Someone was saying over the RT, "Good show, leader. Nice work."

Then it was all over, and at last we were out of range, and there came over us all, I think, an immense feeling of relief and confidence.

As we circled round we could see a great 1000-feet column of whiteness still hanging in the air where our mine had exploded. We could see with satisfaction that Spam had been good, and it had gone off in the right position. Then, as we came closer, we could see that the explosion of the mine 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.

The impression seems to be widespread that the important facts about the operation were, first, the ingenuity of the bomb which was specially designed for it and, secondly, the devastating consequences supposed to have been produced upon Ruhr industry by its success. In truth, neither the special bomb nor the resulting floods were of any great importance. What mattered in terms of historical significance about the dams raid was simply the extreme bomb-aiming accuracy achieved.

This was so because, from the tactics devised and executed in May 1943, by Wing Commander Gibson and the crews of 617 Squadron, there were presently evolved the low level and master bomber techniques which, in 1944, were a prime factor in converting the main force of Bomber Command from a bludgeon into a rapier. This, in turn, meant that when, in the second half of 1944, conditions of air superiority began to arise, Bomber Command stood ready to exploit them with highly accurate and highly effective attacks upon immediately vital targets. It was these precision attacks which injected the decisive element into the great campaign which was waged by Bomber Command throughout the war.

It is with deep regret that I write to confirm my telegram advising you that your son, Squadron Leader Henry Melvin Young D.F.C., is missing as a result of operations.

Squadron Leader Young was a great personal friend of mine and was himself largely responsible for the success of this operation. He was deputy leader of this raid and I watched him drop his load in exactly the right position with great precision. Afterwards we led the raid on the Eder dam and he and I flew on the return journey back to base. Somewhere, however, between the target and the enemy coast he ran into trouble and has not returned.

If as is possible your son was able to abandon his aircraft and land safely in enemy territory, news should reach you direct from the International Red Cross Committee within the next six weeks. Please accept my sincere sympathy during this anxious period of waiting.