This article is an edited transcript of “Johnny” Johnson: The Last British Dambuster available on History Hit TV.
On that Saturday night before the raid, we met as a squadron. The majority of us really met Barnes-Wallis (the inventor of the bouncing bomb) for the first time.
He explained the bomb to us, and showed us film of its development, explained how it had been developed, and how difficult it had been to get it right in the first place.
Then he told us something about the bomb itself. It weighed 9,000 pounds, of which six and a half thousand was explosive within that bomb, fused with two depth fuses to explode at a depth of 25 feet but also fused with a self-destruct fuse. We learned why subsequently.
Then came probably the highest powered briefing I attended throughout my operational career.
The Air Officer Commanding was there. The station commander, Gibson, was there doing the briefing along with Barnes-Wallis, and senior officers of armament and engineering from the station were there. Well, Gibson explained the trip to us.
After Barnes-Wallis’ talk, the conjecture was it was going to be German battleships, notably the Tirpitz, based on the way the bomb had to be dropped. How wrong can you be?
Breaching the dams
The first thing we saw of course were the models of the Möhne and one of the Sorpe. The one on the Eder hadn’t been completely fitted.
We found out what the target was from the models of the dams.
When the bomb was dropped, it was being rotated at 500 revs per minute backwards.
It had to be dropped from exactly 60 feet at a ground speed of 200 knots.
That meant it was sort of four men flying the aircraft, with the navigator watching the lights until everyone was aligned and that was the exact height.
The flight engineer was watching the speed and indicating when it was up or down and the bomb aimer was directing the pilot to the target.
It meant the pilots were being told by three other members of crew how to fly the aircraft, but they didn’t seem to complain too much about it.That was the way it was going to be. Gibson in the briefing explained that he would take off with two others. They’d head for the Möhne and attack it.
When they got there six others, in two sets of three, would follow him and they too would head for the Möhne.
If the Möhne hadn’t been breached by the time they got there they would attack that under Gibson’s direction. When that was breached, they would move over to the Eder. That was the briefing for nine of the crews.
Five, of which we we were one, were briefed for the Sorpe, and of course the Sorpe had to be different from the other two.
It had no towers, so there was nothing to sight on. It was so placed in the hills that a head on attack was virtually impossible, certainly extremely difficult.
We had to fly down one side of the hill with the port outer engine over the dam itself and fly along the dam and estimate to drop the bomb as near as possible to the centre of the dam.
With the port engine over the dam, the bomb was on the water side. Well that meant we weren’t going to use any of the bombing practices we’d been doing for the last six weeks. But that was what we had to do, so that was the job.
We then went back to the messes for the usual operational bacon and eggs meal before you left. Normally, some wit would probably say to you, if you don’t come back, can I have your sausage?
But that sort of thing was taken in good form.
But the sortie was then out to the aircraft, Q-Queen. I know it’s Quebec now, but it was Q-Queen in those days.
But then came our big shock, because it decided it didn’t want to go that night. It developed a hydraulic leak on run up which couldn’t be fixed in time to take off.
There was only one reserve aircraft and that had come in three o’clock that afternoon.
It had been bombed up, fuelled up and it had done a compass swing with the bomb on board to offset the metal of that bomb against the aircraft composition.
As soon as we knew we weren’t going to be able to take Queen, Joe said,
For Christ sake, get that reserve before some other bugger gets there and we don’t get to go.
Header image credit: The King inspects ground crewmen lined up beneath the nose of Avro Lancaster B Mark I, ED989, DX-F, ‘Frederick III’. Credit: Imperial War Museums / Commons.