Re: Bomber Command failure at Urft Dam.
 

My comment was restricted to your slur on Bomber Command for operating the best bombsight available at the time.

However, you have now added " by December 1944 there would have been time to set up Oboe cat and mouse sites in Holland and France to extend Oboe coverage well beyond Berlin at 20,000 ft."

Really? Perhaps they had, I don't know. But what were the requirements for setting up such stations? What were the needs/requirements for such stations, to be balanced against all the other priorities for getting military equipment into Western Europe in those few short - and event-filled - months? Was it quite the easy. open-and-shut case that you present?

I think you meant Belgium and France - we hadn't actually got very far into Holland, and the Germans were still blocking the direct supply routes.

Re: Bomber Command failure at Urft Dam.
 

Graham.

Why the word 'slur'?

Did you read the following in the website I quoted? Note especially the comment about tactical freedom, which was obviously missing when 617 Squadron tried to bomb the Urft Dam but could not find enough clear sky to establish the required length of SABS bomb run, and so failed the mission.
The RAF were obviously concerned about the best (SABS) being the enemy of the good (MkXIV/T1.

"Two other precision bombing squadrons were formed based upon the Mk XlV bombsight, and in the period of February to March 1945 their average error was 195 yards. It is not surprising that when the Norden was offered to the RAF later in the war it was rejected.

Less than 1,000 SABS bombsights were manufactured and after the war great difficulty was experienced in finding sufficient sights to equip two Lincoln squadrons for precision bombing against Japan. Compare this with the 23,000 T1 sights manufactured in America.

There was in Bomber Command at the time much discussion on the comparative merits of the two bombsights. The SABS, although potentially more accurate, lacked the degree of tactical freedom afforded by the Mk XlV/T1. As a result the Mk XlV/T1 was known to Bomber Command as the ‘area’ bombsight of the RAF and the SABS as the ‘precision sight.’

It was a much more complex sight to use and to maintain than the Mk XlV/T1 and required more man-hours in manufacture. For the majority of the squadrons in Bomber Command the Mk XlV/T1 was still the preferred sight."
source: http://www.geocities.com/skidaddy20000/Air-Bomber.html

And I did mean Holland, where 2TAF were experimenting with MRCP and radar controlled bombing at Erp. 2TAF and BC were in the same organization fighting on the same side, but that didn't mean they necessarily spoke to each other.

As for your question about Oboe, I do not know the answer. The RAF had another, and similar system, called GEE-H, which became standard post-war, AFAIK.
The RAF was at the cutting-edge of navigation and bombsight technology. Hence my continued surprise that the cutting-edge 617 Squadron should have been stymied by 10/10th cloud in December 1944. But that's no more than a statement about my ignorance, which has been considerably lessened by this discussion, for which many thanks.

Tony

Re: Bomber Command failure at Urft Dam.
 

"But it remains difficult to believe that BC should have accepted a bombsight like SABS requiring a long visual run. "

If not a downright slur, that's at best an over-critical attitude. It is only "difficult to believe" given the known presence of something superior, which did not actually exist.

Re: Bomber Command failure at Urft Dam.
 

Hi Tony,

I think the crux of the question is establishing what force, applied with what accuracy was required to breach the dams sufficiently in order to achieve the desired outcome of draining them enough to reduce or eliminate the threat to the US 9th Army.

The Tallboy, while seeming to be a powerful weapon, still required delivery to a very high degree of accuracy to be effective because it was a single munition. SABS was the only means, as far as I am aware, that was available at the time to drop the Tallboys and Grand Slams with such a high degree of accuracy. If the 617 Squadron ORB is studied with regard to the raids to breach these dams, two things stand out to me - (1) the bombing with Tallboys was carried out from an unusually (I think) low height, probably due to the restrictions imposed by the cloud and weather, and (2) from the crew reports it appears that some Tallboys may have landed as close as '50 yards' from the dams, without causing the desired breach. These two points are salient because lowering the bombing height would have reduced the effectiveness of the munition (although also potentially increasing the accuracy of delivery) and it would appear that close to a direct hit would have been required the breach the dams.

If you ever see the low angle photo of the results of the first Grand Slam attack against the Bielefeld viaduct on 14 March 1945, it is interesting to see the Tallboy bomb craters very close to the viaduct that were not enough to cause the collapse of the viaduct. The Gland Slam was a direct hit.

The SABS sight, as mentioned, was a very complicated computational bomb sight, so that, besides the need for very accurate flying, a series of measured parameters had to be programmed into the sight before bomb release (and this is where the entire crew of the Lancaster could be involved in the process), and the SABS had to be visually centred on the target. If any one of the measured parameters was inaccurate or changed before bomb release, or if the visual centring of the sight was disturbed, then the bomb could fall wide of the intended aiming point. This fact still holds true today, in spite of much more advanced computational sights, and it has only been the introduction of self course-correcting munitions that has improved single munition accuracy (and, if I remember correctly from various US governmental reports after the first Gulf War, even laser-guided munitions that required visual painting of the target could be disturbed by cloud).

OBOE et al would not, IMHO, have been accurate enough to use for the delivery of Tallboys, and, besides, OBOE can only produce a theoretical bomb release point that probably could not account for all of the variables required for accurate delivery of the Tallboys; many of these variables having to be measured and established in real time during the bomb run.

'Area' raids of any kind (and by this I mean the dropping of a large number of munitions over a given area) have an increased probability of hits provided that the area being saturated includes the intended target. With regards to the dams, I think it probable that while an area attack could have resulted in more hits on the dams themselves, the munitions used would not have been powerful enough the sufficiently breach the dams.

I also think it important to remember that had there had been one clear enough day during that period in December 1944 or at least one 'lucky' hit, the results of the Tallboy attacks against the dams could have been much different (assuming that a direct hit would cause the necessary drainage). Much published literature points to the operational successes of Tallboy, without fully balancing this against the operational failures. I, for one, would be interested to see statistics indicating the average number of Tallboys dropped for each target hit (including those dropped when the target was not hit).

For me, two unanswered questions come out of this discussion - (1) why were no more attempts made after December 1944 to breach the dams (bearing in mind that the weather in January 1945 was similar to December 1944)? (2) why was the plan for the ground campaign not modified in view of the known risk the still active dams posed to its successful execution?

Cheers

Rod

Re: Bomber Command failure at Urft Dam.
 

Quite right. The effort expended matched the direct guidance (instructions) from Eisenhower, the Supreme Commander, up to the point that the weather prevented operations with current technology. The dilution of the bombing offensive against Germany was not popular with Harris, but the squadrons flew every possible mission in all theatres, including the unpopular ones. Discussions about bombsights never stopped a mission from being mounted, but weather did. A high profile failure to complete an assignment that was technically feasible would not have helped Harris in any way in his dealings with Eisenhower or Churchill, and it has been competently demonstrated that there was no reasonable expectation of success for the destruction of the Urft Dam using the weapons available. Who knows what would have happened if other weapons or technology had been accesable, but obviously they weren’t.

Bruce

Re: Bomber Command failure at Urft Dam.
 

Rod,
A timeline might provide some kind of answer to your two questions (why BC attempts stopped, and why the ground campaign was not modified).
September 25, Market Garden failed and 21 Army Group was ordered to concentrate on clearing the Scheldt. Since they had Groesbeek, they began to plan Op Gatwick, an attack through the Reichswald to Wesel (became Op Veritable).
September 25, 1 US Army (Hodges) was told to reduce the salient on the west bank of the Maas (he failed), and to drive to the Rhine between Dusseldorf and Bonn through the Aachen gap.
October 2, Aachen attacked instead of bypassed. Huertgenwald entered.
November 3, Schmidt taken, only 2 miles from Schwammanauel Dam.
November 7, major attack towards the Roer.
November 11, Hodges first realised the significance of the Roer dams, when a German map was captured showing the flooding consequent to dam destruction. If Hodges had realised the significance earlier, he might have taken the dams by attacking up the Monschau corridor on October 2, instead of entering the Huertgenwald (where his forces were bled white with 24,000 casualties and 9,000 cases of trenchfoot and battle exhaustion). But instead of taking the dams after November 11, Hodges asked for their destruction by the strategic bomber forces, which Ike ordered. “After several bomber strikes failed to destroy the dams, however, all air effort ceased, much to the disappointment of Hodges who continued to advocate air action in his unshaken belief that a 1,000-plane raid could do the job”.
December 10, Hodges ordered the dams taken.
December 16, Ardennes offensive intervened.
February 5, Hodges ordered the dams taken in support of IX USArmy's attack across the Roer in Op Grenade scheduled for February 9. 375,000 US troops waited to cross the Roer in a pincer movement coordinated with 21 Army Group's Op Veritable, scheduled for February 8.
February 5, little progress by Hodges' troops towards the Schwammanauel Dam.
February 6, at 1800 hrs an engineer company broke through and raced for the dam. They arrived at midnight to find the valves destroyed in the open position to release a continuous flow until the reservoir was emptied over several days. Why US engineers did not then blow the dam is unknown, and I have not seen the question asked. “First Army's neglect in seizing the dams was only eclipsed by the casual admission by Hodges that he never really expected success anyway. Kay Summersby – Ike's driver and mistress - noted that “E always thought this would happen”.
February 8, Veritable opened.
February 13, Roer peaked at 11 feet.
February 15, Roer began to subside.
February 21, Simpson decided to cross on February 23.
February 23, first boat across at 0330hrs, 3 footbridges destroyed before one survived at noon, treadway bridge completed at 2000hrs but destroyed by German aircraft at 2015hrs.
February 24, first treadway in use at 1100hrs. Attacks made by 97 LW sorties including Me262 (presumably KG54, and their first sorties?) and four fighters with US markings assumed to have been operated by the LW.
Quotations are from the Whitakers' book, Rhineland.

Tony

Re: Bomber Command failure at Urft Dam.
 

Rod,

A specific answer to your first question is given in Ellis' Victory in the West, Vol II, page 164; "On the 12th of December SHAEF stopped the bombing because it was diverting too much effort from strategic targets".

Ellis also says that SHAEF "hoped that BC would be able to repeat its success against the earth dykes of Walcheren".

This success occurred on October 3, when 259 Lancasters and Mosquitos aimed 1,270 tons of HE on the dike at Westkapelle. When a 100-yard breach was observed with the sea pouring through, the Master of Ceremonies ordered ten Lancasters carrying Tallboys to return to base without releasing their bombs.

Cheers, Tony

Re: Bomber Command failure at Urft Dam.
 

Just a couple of comments regarding the previous posts. 617 Squadron Lancasters that carried tallboys could not be equipped with H2S. I have correspondence from Harris, Cochrane, Bennett, Saunby and others discussing this and also equipping Lancasters with Oboe, which also could not be fitted on a Lancaster with H2S.
While Oboe equipped aircraft could drop bombs or target indicators with the same accuracy in any type of cloud (the Oboe crews never used any visual references on a bombing run), the main force aircraft bombing the Oboe TIs were greatly affected by cloud. Sky marking was much less accurrate than groundmarking and the winter season Oboe attacks were on the whole less successful due to the weather.
Mobile Oboe transmitters certainly extended the range and allowed Oboe operations to eventually hit Berlin but the extended range did not translate into lower operating heights for the Oboe crews unless they were leading formations of aircraft. Typically Oboe Mosquitoes operated from 28,000 to 34,000 feet. Even with close targets in the Pas de Calais, when sometimes their bombing runs began over the Thames estuary they generally operated over 20,000 feet. Height gave them protection as well as range and they were still able to maintain their accuracy. One example was the D-Day attack at Pointe du Hoc just a few hours before the Americans came ashore. 3 Oboe Mosquitoes marked for 114 Lancasters, 1 from 30,000 feet, the other 2 from 18,000. The Mosquito at 30,000 had a target error of 70 yds., the 2 at 18,000 had target errors of 140 yds. and 220 yds.
Dave Wallace

Re: Bomber Command failure at Urft Dam.
 

Although this thread seems dormant it has been most interesting reading particularly since my father was the sole survivor of LM637 LE-V shot down over the Urft Target area 8th December '44.
A few years ago I visited the area to get some background and context to the raids on the Urft. Adverts were placed in the local newspapers asking for information and we were put in touch with local historians and the water company who manage the dam gave us a guided tour of the inner passages in the dam.

According to the water company engineers, who recently have blasted further inspection galleries, it would have been impossible to destroy because the rocks used in construction were so tough, it gave them big problems in driving the extra galleries.

I have put together a storyboard with some interesting photos of the dam and nearby craters

https://www.facebook.com/media/set/?...3&l=eb5f4ee42d

Re: Bomber Command failure at Urft Dam.
 

Hi Tony,

There is a pile of correspondence on these dams between Bert Harris, Portal and SHAEF in the Harris archive. I recall seeing them when I was doing some work for the BCM.

Kind Regards

Andy Bird