70th anniversary of "Colossus" at Bletchley Park. (WW2, war, Rome)

[Mr Blue Sky]

A quite remarkable achievement at the time. I consider it difficult to underestimate the contribution to the war effort (WWII) of it and Bletchley Park in general. It later became the basis of the UK's GCHQ cyber-intelligence operation.

BBC News - Lifting the lid on a Colossal secret [contains two videos].

As the code-cracking Colossus celebrates its 70th anniversary, John Cane, a former Post Office engineer who helped maintain it, reminisces for the first time about working on the pioneering machine. His testimony gives a glimpse into the early days of GCHQ's efforts to employ technology in its spying efforts.

Also:

Bletchley Park
UK spooks STILL won't release Bletchley Park secrets 70 years on
WW2 codebreakers - the final secret - Telegraph
BBC - History - Bletchley Park (pictures, video, facts & news)

[Felix C]

Regarding Enigma/Ultra where do you see the resulting information tremendously benefited the Allies compared to if deciphering the signals in question did not occur?

I ask because Uboats and the Battle of the Atlantic are usually mentioned by I would posit it was air cover, radar, HFDF use and more and well trained surface escorts that mastered the Uboats not decoding their signals.

Ah, this is alternative history stuff again........

[NJGOAT]

Originally Posted by Felix C

Regarding Enigma/Ultra where do you see the resulting information tremendously benefited the Allies compared to if deciphering did not occur?

I ask because Uboats and the Battle of the Atlantic are usually mentioned by I would posit it was air cover, radar, HFDF use and more and well trained surface escorts that mastered the Uboats not decoding their signals.

Ah, this is alternative history stuff again........

Not really, I think it's an interesting question. People often refer to it as being a game changer, but there are only a few operations whose success was really credited to Ultra. In general Ultra did not provide "current" intelligence and was often delayed and there were many moments, where they simply could not decipher anything. When they did have breakthroughs though they tended to act on them.

The first actionable Ultra intelligence was the German buildup in 1941 prior to the invasion of Greece. However, the allies lacked the resources to do anything about it. The reading of naval transmissions in the same year contributed to the British Med Fleet's defeat of the Italian navy at Matapan. Alexander heavily credits it for assisting in the defeat of Rommel in North Africa in 41/42 as Ultra provided precise details on his force disposition, movements, supply situation and capability.

It was marginally succesful in 1941 in helping to steer convoys around Uboat packs and in a small number of cases direct ships and planes to ambush Uboats. You are quite right that Ultra really had little impact on the Battle of the Atlantic versus improvements in ASW tactics.

Some claim that it "shortened the war" but these are often based on hypotheticals like Rommel capturing Egypt in 1942 which was highly unlikely with or wthout Ultra.

[Felix C]

I was thinking of either 1st Alamein or Mortain and the targeted sinking of supply ships to NA during the critical periods when fuel were needed for mobiity at the front that Ultra was useful but have to consider if they would have made the difference. Gains eastward from Alamein stretching supply lines further and the difficulty in transporting fuel from Bengahzi, Tripoli or Tobruk eastward. I recall reading that Kesselring wrote Rommel had plenty of fuel during late 1942 but it was at Tobruk. Do not know if K. was exagerrating.

Regarding Mortain, U.S. Army being on the defensive would have terrain use benefits previously used by the Germans to stop the attack. Plus air superiority.

I recall reading how Rommel confounded the Allies because they would read his instructions from seniors, Rome or Berlin, but he would act in an independent manner and so strike when unexpected.