In the middle of March 1943 Squadron Leader Guy Gibson had been quietly transferred from his Lancaster bomber squadron. He and a select group of experienced Lancaster crews were to form No 617 Squadron and had just a matter of weeks to undertake some secret training. The main force of Bomber Command were then fully engaged in the Battle of the Ruhr, an attack on the heart of German industry.
No. 617 Squadron’s contribution to the Battle of the Ruhr was a very special target to be attacked by very special means. They were to attack the critical hydro electric power that served the region, by attempting to blow up the dams that provided the power. It was expected that the release of the reservoir water would also do immense damage. And they were to do so by dropping a unique weapon, never before used in combat – the bouncing bomb invented by Barnes Wallis.
The bombs would bounce over the nets protecting the dams and, because they were rotating, drive themselves down the wall of the dam until they reached the optimum depth to explode – causing a rupture in the dam wall.
Delivering such bombs called for special techniques. They had to be dropped from exactly 60 feet – determined by the point at which two spotlights shining down from the aircraft intersected. All the time the illuminated aircraft would fly straight and level into a wall of flak.
Guy Gibson himself was to leave an incredible description of those final moments before bomb release:
Terry turned on the spotlights and began giving directions – ‘Down-down-down. Steady-steady.’ We were then exactly sixty feet.
Pulford began working the speed; first he put on a little flap to slow us down, then he opened the throttles to get the air-speed indicator exactly against the red mark.
Spam began lining up his sights against the towers. He had turned the fusing switch to the ‘ON’ position. I began flying.
The gunners had seen us coming. They could see us coming with our spotlights on for over two miles away. Now they opened up and their tracers began swirling towards us; some were seen bouncing off the smooth surface of the lake.
This was a horrible moment: we were being dragged along at four miles a minute, almost against our will, towards the things we were going to destroy. 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 – this 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 bomb-sight 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 see us quite clearly now. It was not exactly inferno. I have been through far worse flak fire 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. My aircraft was very small. 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 tracers flashing past the windows – they all seemed the same colour now – and the inaccuracy of the gun positions near the power-station; they were firing in the wrong direction.
The closeness of the dam wall. Spam’s exultant, ‘Mine gone.’
Hutch’s red Very lights to blind the flak gunners. The speed of the whole thing.
Someone 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.