Final briefing for the crews began at 6pm. Gibson introduced Barnes Wallis and gave the crews details of the targets and full details of the plans. The first wave of nine aircraft were destined for the Möhne, Sorpe and Eder dams and they would leave the grounds in three groups of three at 10 minute intervals. The second wave comprising five Lancasters would fly straight to the Sorpe whilst the third wave of five aircraft would take off 2½ hours later to act as a backup.
The briefing took two hours and all crew came away with full details of their tasks for the night.
View the operational order in PDF format by following this link: Operations Record Book
Details of the crews take off times and other information as it was recorded in the squadron operational record book after the raid are available in the operational record book
It should be remembered that the operational records book was compiled at the time and keeping accurate records was not the main concern. Consequently some of the names, ranks and other information is not always as accurate as it could be. In broad terms, it gives a good picture of the detail of the operation, with take off times, bombing times and landings. Equally much information particularly about casualties was not known at the time and new information that has come to light since has been added in italics.
At 21:28 hours the first aircraft of the second wave (AJ-E) started its take off run. As the second wave was taking a northerly route to the targets they had a longer flight path and consequently left the ground before the first wave. Operation Chastise had begun.
All of the aircraft took off normally. Flight Lieutenant Joe McCarthy in AJ-Q was not able however to take off. His pre-flight checks revealed a coolant leak in the number 4 engine and consequently the whole crew changed to one of the reserve aircraft AJ-T and suffered a 20 minute delay in doing so. At 21:39 Gibsons Lancaster took off. The first wave passed through the Balkan area they encountered heavy flak and intense searchlight activity. This caused Gibson to break radio silence and issue a flak warning which Five Group rebroadcast to all the aircraft shortly afterwards with a detailed position report. There was also heavy flak to the north of Hamme on the approach to the railway marshalling yards.
The second flight of three aircraft of the first wave also encountered flak near Dülmen. The last flight of the first wave encountered stronger headwinds and consequently they were slightly late as they crossed the Dutch boarder into Germany. AJ-B piloted by Flight Lieutenant W.Astell were flying as low as they could to avoid the flak and search lights, but hit high tension wires and pylons 4km from Marbech. The aircraft reared up in the air, burst into flames, but then crashed to the ground. Two minutes later the mine exploded and all seven crew were killed. Operation Chastise had claimed its first casualties.
Gibson arrived over the Möhne reservoir at 00:15 hours. The aircraft assembled in an anti-clockwise holding pattern 10 km south of Völlinghaussen whilst Gibson called AJ-B on the radio. Astell and his crew were already dead, but he did not know this. Gibson took a few moments to assess the target and its defences. It appeared to be as he had been briefed with three light flak batteries on the dam wall and three more in the valley. Gibson confirmed the attack would be carried out as planned by radio. Using the VHF radio Gibson assigned five of the remaining eight Lancasters to the attack. Gibson prepared for his run in, the weapon already having been spun up to speed by his W/Op. He first made a dummy run towards the dam to get the lie of the land. He flew through the flak fire before reporting on the VHF that “he liked the look of it”.
The attack run had been planned to allow the aircraft time to organise their direction, height and speed before crossing a spit of land that jutted out into the lake and becoming visible to the opposing flak guns. His Lancaster turned out of the holding pattern and directly towards the dam face over the landmark spit of land that guided the run in. His bomb was dropped at 00.28hrs and was watched by the rear gunner yo bounce three times before exploding against the dam face and throwing a vast column of water into the air. The bomb had struck approximately 150ft off the centre of the face of the dam and the dam had not collapsed.
Hopgood in AJ-M attacked next. The spotlights came on and he commenced his run into the now awaiting flak from the shore and the towers. The Lancaster was hit and started to burn on the port outer engine. Gibson noted damage to the port inner as well. Additionally the starboard wing had received hits as well and it is little wonder that with these distractions the upkeep was dropped just a few seconds late, it hit, bounced and flew right over the top of the dam wall before exploding with a great violence down by the power generating house in front of the dam wall. A red very light was fired by Hopgoods W/Op and by now the Lancaster was brightly aflame from a petrol fire. The aircraft climbed to about 500ft and then the strain became too much and the Starboard wing collapsed sending the plane into a bright dive to crash and explode near the village of Ostonnen, 6km North West of the dam. Gibson noted that he thought some of the crew may have survived and in fact three survived the crash and two survived to become POW’s. Burcher, the rear gunner jumped with his parachute open and in his arms and survived and F/Sgt Fraser the bomb aimer also made it out using the same method due to the low height of the aircraft. Minchin, the W/op was pushed out by Burcher but the altitude was too low and his parachute did not open in time to save him.
Martin in AJ-P commenced his run with Gibson flying alongside in an attempt to draw away the heavy volumes of light flak coming from the dam. His bomb threw up a similar large plume of water, but again the dam held.
Squadron Leader Dingy Young took the fourth attack in AJ-A. Martin flew parallel with him and instructed his gunners to take on the flak towers to try and reduce the amount of light flak. The guns had been loaded with all daytime tracer ammunition which made the fire appear much heavier than it actually was. Gibson at the same time turned all of his lights on and flew over the dam from the south in a further attempt to draw the flak away. Again a tremendous plume of water but no break in the dam.
AJ-J piloted by Flight Lieutenant Maltby preceded his run for the fifth attack. Gibson and Martin flew alongside to take on the flak and Maltby’s bomb was perfectly placed. This time a plume of water shot to over 1,000ft into the air before collapsing back into the lake. The dam appeared intact and Gibson ordered Shannon to commence the sixth attack. Whilst this was happening the main wall of the dam collapsed revealing an enormous breach through which poured millions of gallons of water. All the anti aircraft fire, save that from one gun ceased and the code word for a successful breach of this dam ?Nigger? was transmitted to bomber command. The aircraft circled for a few minutes watching in awe as the torrent of water travelled down the valley, in some cases with the headlights of cars visibly being overwhelmed by the water and slowly turning green, then brown, before disappearing. The operation however had to continue.
Maltby and Martin then set course for home whilst the three aircraft still with their Upkeeps (AJ-L, AJ-Z and AJ-N) flew to the south east accompanied by Gibson towards the Eder reservoir. This was about 12 minutes flying time away. This journey was made without opposition although in the moonlight identification of the dam itself proved initially quite difficult. The approach to this target was difficult dropping down past Waldeck Castle into a valley flying towards the Hammerberg spit of land in the lake and then turning 90° left for a short run onto the dam face. The Lancasters started by circling into an anti-clockwise direction over Waldeck Castle and Shannon was given the task of the first attack.
AJ-L made three unsuccessful attempts to get the right position. Shannon was having problems achieving the required height and approach angle, so Gibson put him into a holding pattern and called Maudslay in AJ-Z. He also had tremendous problems getting into position and Gibson ordered him to hold off. He put Shannon back onto the task and he made two further attempts before on the third he was able to drop the Upkeep. It bounced twice and exploded south of the dam without producing any visible result whatsoever.
Maudslay then came in again and he released his Upkeep during his second approach. He dropped his weapon slightly too late and it hit the crest of the dam and exploded with a brilliant flash lighting up the countryside for miles around. The explosion occurred right behind Maudslays Lancaster which had just crossed the crest of the dam, and Gibson tried to raise him on the VHF. Other crew members reported hearing a weak unnatural, almost dismembered voice in reply and at the time it was believed that Maudslay had crashed, his aircraft having been damaged by the blast. In practice, however he had struggled away with a damaged aircraft and started on the return journey, but he was shot down by light flak at 02:36 at Emmerich-Klein-Netterdn. Maudslay and all of his crew died.
AJ-N, piloted by Les Knight was then ordered to make its approach. The bomb bounced three times and struck the dam to the south of the centre and exploded with Gibson flying alongside to suppress the flak. The blast visibly shook the whole dam and then the central wall collapsed, allowing thousands of cubic yards of water to roar through the breach.