In WWII Life magazine published an article about the US Navy’s submarines in the Pacific, saying that Japanese depth charges were set too shallow. Unfortunately it was true, and the Japanese learned to reset the charges soon after the article appeared. It may have sunk at least one US sub afterwards.
Also, the common Australian wasn’t nessesarily 100% into WWII, suffering labor troubles throughout the conflict. While there likely wasn’t any direct effect, the repeated labor slowdowns were well reported and amplified in the Axis press and repeated to the prisoners of war, including the one in Thailand made famous by the “Bridge Over the River Kwai,” that had a negative effect on morale.
Even if no direct cases can be made, the government put out the numerous posters because it was a darn good idea to do so. We can never prove what might have happened if people weren’t constantly reminded to not talk about anything that may, however loosely and inadvertently, be of use to the enemy, but why in the world take the chance?
Ted Striker: My orders came through. My squadron ships out tomorrow. We’re bombing the storage depots at Daiquiri at 1800 hours. We’re coming in from the north, below their radar.
Elaine Dickinson: When will you be back?
Ted Striker: I can’t tell you that. It’s classified.
My ex boss was a fighter pilot in WWII, with an attitude and a mouth, like many pilots do. During his flight training, they were told in no uncertain terms they must never tell anyone about the size of the class, because that was classified. He spoke up: “Are you serious? You think our families and girlfriends are spies? If someone wants to know the class size, all they need to do is ask the local florist how many corsages they sold at graduation!” Needless to say, this did not go over well. The powers that be missed the point, and solved the problem with a “no corsage” rule.
Again, this was exactly the right thing to do. Working out troop movements from secondary and tertiary sources was a major practice of the intelligence services during the war, and any good book on them will provide lots of examples. TPTB got the point perfectly. It just took time for the point to percolate itself throughout the military, because pre-war thinking never allowed for this.
In WWII Life magazine published an article about the US Navy’s submarines in the Pacific, saying that Japanese depth charges were set too shallow. Unfortunately it was true, and the Japanese learned to reset the charges soon after the article appeared. It may have sunk at least one US sub afterwards.
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The following is from the Wikipedia article on “Depth Charge”:
Pacific theater
In the Pacific, Japanese depth charge attacks initially proved fairly
unsuccessful against U.S. and British submarines. Unless caught in
shallow water, a U.S. submarine commander could normally dive to a
deeper depth in order to escape destruction.
The deficiencies of Japanese depth-charge tactics were revealed in a
press conference held by U.S. Congressman Andrew J. May, a member
of the House Military Affairs Committee who had visited the Pacific
theater and received many intelligence and operational briefings.
Incredibly, May mentioned the highly sensitive fact that American
submarines had a high survivability rate because Japanese depth
charges were fuzed to explode at too shallow a depth.
Various press associations sent this leaked news story over their
wires, compounding the danger, and many newspapers (including one
in Honolulu, Hawaii) published it. Soon, Japanese forces were resetting
their depth charges to explode at a more effective average depth of 75
m (250 feet), to the detriment of American submariners. Vice Admiral
Charles A. Lockwood, commander of the U.S. submarine fleet in the
Pacific, later estimated that May's revelation cost the United States
Navy as many as ten submarines and 800 seamen killed in action. [5]
The footnote [5] is a citation to:
5. Blair Jr., Clay, Silent Victory: The US Submarine War against Japan,
Annapolis, Maryland: Naval Institute Press, 2001.
But if you follow the link to the bio of Andrew J. May, they restate the
above (with a citation to the same source) and add the following:
Other historians claim that the May Incident never happened, and that
the Japanese never discovered U.S. submarine depth capabilities
during the war. [4]
The footnote [4] is a citation to:
4. Norman Friedman (1995). U.S. Submarines Through 1945. Naval
Institute Press. p. 355. ISBN 1557502633.
An example of this, not involving ships, was Los Alamos. While what was going on there was highly classified, the ticketmaster of the Princeton Junction train station was well aware of it, since he sold an extraordinary number of tickets to Princeton physicists, including Feynman.
But surely the Japanese Navy already were aware of this – they were the ones dropping the depth charges, after all. This info, when it reached the Japanese, was probably just confirmation of what their naval commander already knew.
After all, we had the same problem when Germany came out with their advanced (Type III?) submarines. They could dive deeper than previous ones, lower than allied depth charges were set. (In fact, some types of depth charges then in use could not even be set to go that deep.) But the allies figured this out on their own, without any leak from any German politician. (Our decrypts of their communications might have been helpful, but I’ve never seen that mentioned. Given the need to keep radio messages short, submarines probably didn’t go into detail about depth charging over the airwaves.)
Yes, it tended to be fairly obvious whether a depth-charge attack had succeeded or not. The classic example of adjusting the explosion depth to produce better results in the Battle of the Atlantic was based on the analysis by “Blackett’s Circus” of attacks where the charges were being dropped from aircraft. There weren’t any intelligence reports used in suggesting or proving the improvement - just brains and the observations from the crews in the planes.
Which isn’t an argument against security measures. The very fact that such analyses could be worthwhile wasn’t initially obvious to everyone at the time. On both sides.
Why were corsages involved in the first place? Were the graduations public ceremonies? If so, it seems like what was called for was a “no graduation” rule.
Even if the graduations weren’t public, if corsages posed a problem then who knows what else may have. A total ban on such ceremonies seems in order, so as to cover all bases.
No, the Japanese weren’t very good at figuring this kind of thing out. They thought escorting merchantment to be above them until their losses piled up in late 1943, and then their convoys were poorly treated. Japanese depth charges had worse mechanical problems than American torpedoes, in fact.
By the time the Germans deployed more advanced vessels, the allies were using the contact-detonated hedgehogs almost exclusively.
The German U-boats were stalking our harbors, notably Mobile Alabama and New York City. In fact, one stealthy commander would wait for a ship to eclipse an onshore NY light as his cue to fire torpedoes.
I heard the the interview on NPR (Diane Rehm show) yesterday about the damage that Wiki-Leaks might cause. Al Qaeda can learn our procedures and responses, names of informants, etc… Military Censors today probably use on civilian contractors to do the work.