During the 1930s Adolf Hitler came to power in a politically fragmented and bankrupt Germany. During the following years it became apparent that Hitler was rebuilding Germany following the First World War and had military ambitions which made the country a threat to those about them and their allies. Most of the central European countries were catalysed (to varying degrees) by these developments and Great Britain commenced a late, but timely re-armament program.
It is fair to say that the operation to destroy the German dams in the Ruhr began on Tuesday July 26th 1938 at a meeting chaired by Air Vice Marshall W. Sholto Douglas, Assistant Chief of the Air Staff. This was a meeting of the RAF Bombing Committee and one of the main items on the agenda was to bring to the meetings attention, a potential weak point in the German industrial economy. This potential weakness was a number of reservoirs that supplied power and water to manufacturing industries which
in the time of war would be turned over to war manufacture. The object of the meeting was to enquire into the extent to which effective air action against the Dams of the reservoirs until similar targets would be possible. Bombing Committee paper number 16 was circulated and this document described the types of construction and siting of the Dams along with notes on the potential damage that was caused by a number of the air dropped weapons then available. S/L C G Burge representing the Air Targets Sub-Committee of Aerial Intelligence reported that the amount of water consumed in the whole of Germany was only three times that of the Ruhr and that the bulk of it was obtained from one large reservoir contained by a single large dam known as the Möhne Dam. He added that there were also four or five other reservoirs in Germany which fed the inland waterways. The destruction of which was likely to leave the waterways high and dry which would severely effect the German transportation system. It also seemed reasonable to believe that the damage caused would be extremely difficult to put right.
At this stage all discussion was about bombing the dams with existing weapons. The largest of these was then the 500lb semi-armour piercing bomb designed to be used against ships. When dropped from a sufficient height, it had penetrated in tests 5ft into concrete and the thickness of a dam at a depth of 40ft was estimated to be approximately 12ft. It was felt that if a bomb could be driven into the wall to a depth of 5ft, the remaining 7ft should be severely damaged or breached but no discussion was given to special weapons. It was recognised during the meeting that any bomb would be far more effective when placed on the wet side of the dam, rather than the dry side. The possible use of torpedoes was also discussed. The final outcome of the meeting was that at the present time it is considered that the attack should be directed primarily against the high water side of the dam. Attack against the lower side is considered less likely to be effective unless a bomb can be devised that which will develop sufficient striking velocity to achieve the necessary amount of damage at low altitude.
The seed had been sown and then matters rested for three years. In essence however the basis of Operation Chastise had been established.
1.That the destruction of the Möhne dam would remove a large percentage of the water required by the Ruhr Valley industries to produce war materials along with a substantial amount of hydro-electricity.
2.The destruction of the smaller Ruhr dams would cause some loss of electrical power and great disruption to the German inland waterway system upon which a great proportion of German industry and war making capability depended.
3.An additional fringe benefit would be the damage caused to industry and infrastructure by the release of large amounts of water from these reservoirs.
Source: http://www.dambusters.org.uk/
So the question became what kind of bomb could be used and how would it be deployed? The major challenge lay in the location and siting of the dams.
The three main targets were the Möhne, Eder and Sorpe dams.The Möhne dam was a curved ‘gravity’ dam and was 40m high and 650m long. There were tree-covered hills around the reservoir, but any attacking aircraft would be exposed on the immediate approach. The Eder dam was of similar construction but was an even more challenging target. Its winding reservoir was bordered by steep hills. The only way to approach would be from the north. The Sorpe was a different type of dam and had a watertight concrete core 10m wide. At each end of its reservoir the land rose steeply, and there was also a church spire in the path of the attacking aircraft.
In 1942 British engineer Barnes Wallis began working on plans for a bomb that could skip across water.
He developed the idea by experimenting with bouncing marbles across a water tub in his back garden. Wallis thought the new weapon could be used to attack moored battleships, but research soon focused on using it against the dams that were vital to German industry.
The Admiralty and the RAF carried out extensive tests at sites around the country. These revealed that the drum-shaped bomb (codenamed ‘Upkeep’) needed to be dropped from a height of 60 feet (18m), and at a ground speed of 232mph. The bomb would spin backwards across the surface of the water before reaching the dam. Its residual spin would then drive the bomb down the wall of the dam before exploding at its base. All that was needed now was men to fly specially modified Lancaster bombers which would carry the ‘Upkeep’.
In late March 1943, a new squadron was formed to carry out the raid on the dams. Initially codenamed Squadron X, 617 Squadron was led by 24-year old Wing Commander Guy Gibson (pictured in door of aircraft) and was made up of aircrew from Britain, Canada, Australia, New Zealand and the USA. With one month to go before the raid, and with only Gibson knowing the full details of the operation, the squadron began intensive training in low-level night flying and navigation. They were ready for Operation ‘Chastise’.
From 9.28pm on 16 May, 133 aircrew in 19 Lancasters took off in three waves to bomb the dams. Gibson was flying in the first wave and his aircraft was first to attack the Möhne (pictured here) at 12.28am, but five aircraft had to drop their bombs before it was breached. The remaining aircraft still to drop their bombs then attacked the Eder, which finally collapsed at 1.52am. Meanwhile, aircraft from the two other waves bombed the Sorpe but it remained intact.
Of the 133 aircrew that took part, 53 men were killed and three became prisoners of war. On the ground, almost 1,300 people were killed in the resulting flooding. Although the impact on industrial production was limited, the raid gave a significant morale boost to the people of Britain.
Excerpts from: https://www.iwm.org.uk/history/the-incredible-story-of-the-dambusters-raid
The Canadian contribution
There were 30 Canadians (and one American who flew for the RCAF) who flew with Operation Chastise. They included:
Flight Lieutenant Joseph Charles “Joe” McCarthy, an American, was a member of the RCAF and a pilot during the raid. He was awarded the Distinguished Service Order. He survived the war, remained in the RCAF and eventually became a Canadian citizen.
Source: http://www.rcaf-arc.forces.gc.ca/en/article-template-standard.page?doc=operation-chastise-the-dambusters-raid/hv9861zq