David, I do not know how much of the ULTRA material was useless, but I do agree that much incidental material was gathered in the hunt for the part that was valuable. During the pre-bombe days at BP, 'the more the better' was the rule because of the increased likelyhood of finding a crib, or way into the Enigma settings used. Somehow though I don't think that is what you were addressing.

SIGINT was the intelligence weapon that allowed the Allies naval and air forces to be in the right place at the right time, and ULTRA was a major part of that weapon. However, much as Ken said, it is pointless to try to give the lions share of the credit to one part of the winning combination, rather like saying which is the most important leg on a three-legged stool.

My take on the value of ULTRA? It was the most sought after, expensive and rewarding of the intelligence prizes, but it’s value is still ill-defined and there are serious flaws in any argument that appraises ULTRA without putting it into context within SIGINT. There could have been no ULTRA without the Y Service organisation which listened to literally thousands of Axis transmissions daily, and faithfully recorded the chosen targets for analysis. Analysis included decryption, but the knowledge gained began with identifying who did or did not broadcast, where they were, and whether they were acting in a routine or irregular manner.

During the Battle of the Atlantic, if a convoy was under threat, the tracking room in London was given data by secure telephone links from BP. This allowed the convoy and U-boat plots on the wall-sized map to be updated, often kept up to the minute. There was no visible distinction between plots gleaned from d/f information, ULTRA decrypts, or visual sightings. If the Naval Advisor at BP passed the information as current and reliable, then its source was only mentioned if, in the view of the Advisor, it was relevant to the process at London. The background was there if asked, but not part of the original message. The written and teleprinted reports for the cooler job of assessing the value of data included the source, and ULTRA was highly valued because, as is evident, it was straight from the German message pads. However, the value of SIGINT as a whole, in my opinion, revolved around the ability of BP to correctly interpret the sources of Y Service intercepts, whether broken or not. The amount of information gleaned from the simple act of hearing the transmissions, before they could be broken, was sufficient to identify the majority of KM and Italian vessels, and there were very few land bases that did not inadvertantly give vital information about ships at sea by their routine transmissions.

This is where the strength of the Allied intelligence structure is clear: in the co-ordination and correct interpretation of the various sources of information. Because ULTRA is now in the public eye, it has been thrust into the paramount role in this story. Partly because the principles of SIGINT analysis that were developed from 1940 onwards remain valid today, there are many documents relating to WWll Allied SIGINT that are still classified. I have tried to gain access and, frankly, I do not believe we will ever see them.

But of course, that is just my opinion.

Bruce