# Did The germans Tap TransAtlantic Phone Cables in WWII? **URL:** \ **Category:** Factual Questions\ **Created:** [December 20, 2003, 2:03am UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099 "2003-12-20T02:03:56Z")\ **Posts on this page:** 18\ **Page:** 3
**Author:** ![Terry\_Kennedy](https://avatars.discourse-cdn.com/v4/letter/t/c57346/32.png) [@Terry\_Kennedy](https://boards.straightdope.com/u/Terry_Kennedy)\ **Post date:** [June 6, 2011, 2:00am UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/41 "2011-06-06T02:00:06Z")
> [@focusoninfinity](#): > > Are the galvanic (vs. fiber-optic) cables still in use? Are both galvanic and fiber-optic one-way? Does this mean each cable must be dedicated to one direction, or all traffic one-way must stop, to transmit in reverse? Somewhere around here I have the final issue of the AT&T Submarine Systems wall poster, before they got sold off in 1997, showing all of the undersea cables. There’s a story that most copies of this map were called back and destroyed because of the detailed amound of labeling on them - I don’t know if that is true. I don’t believe there are any copper cables carrying civilian undersea voice or data traffic at this point. In the not-too-distant past, there were still some being used for other purposes. You can send data in both directions simultaneously on both copper and fiber. There were a number of different methods to do this on copper. For a good read on the older systems, I recommend “Transmission Systems for Telecommunications” from Bell Labs (1959). On fiber optic cables, the normal method is to use different frequencies of light (search for CWDM or DWDM). This equipment used to be quite expensive and would only be used when the cost of the fiber link was even more expensive, but the cost has come way down. You can get equipment to multiplex 8 to 12 signals over a single fiber for under $1000 now. You can get a SFP transciever for Gigabit Ethernet that carries a link over a single fiber for around $40 (search for “1000BASE-BX10”). Back on the original topic - the Germans were able to decrypt the simple encryption (A-3 scrambler) used on the earlier Churchill / Roosevelt radiotelephone calls. They simply set up a radio listening station on the Dutch coast and eavesdropped. The solution was a SIGSALY (“Green Hornet”) encrypt/decrypt device. [Reference](http://cwr.iwm.org.uk/server/show/ConWebDoc.5795) For more info, I suggest “National Service in War and Peace (1925–1975)” which is also a Bell Labs book. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [June 7, 2011, 4:36pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/42 "2011-06-07T16:36:14Z")
> [@t-bonham@scc.net](#): > > I would certainly believe that Churchill & Roosevelt would have been speaking in English. > > Hitler was a rather uneducated former housepainter. I’ve never heard that he could speak English. So I rather doubt that this is true. Um. You do know, don’t you, that as head of state, Hitler had people working for him, some of which spoke English and could translate? He also had decryption and code breakers working for his intelligence agencies. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [June 7, 2011, 4:38pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/43 "2011-06-07T16:38:47Z")
> [@wevets](#): > > German submarines hunting close to the transatlantic cable should be no surprise, though. Shipping will want to minimize fuel consumption and, during wartime, time spent in vulnerable sea areas far from land. Cable placers will want to minimize the length of cable, especially underwater where repair costs will be higher, thus it should come as no surprise that cable is near shipping is near U-boats hunting. Actually, no. Cable companies want to lay the shortest route, true. But for ships, even with engines, the longer route may be the quicker one, due to wind or current. A ship going against the Gulf stream or the trade winds would spend a lot more fuel and time fighting them than getting forward compared to a ship going around. Have you ever looked at the map of the slave-triangle in the days of sailing ships? It’s not the shortest geographic route, but the quickest because of the trade winds. ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [June 7, 2011, 5:20pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/44 "2011-06-07T17:20:22Z")
> [@Terry\_Kennedy](#): > > Somewhere around here I have the final issue of the AT&T Submarine Systems wall poster, before they got sold off in 1997, showing all of the undersea cables. There’s a story that most copies of this map were called back and destroyed because of the detailed amound of labeling on them - I don’t know if that is true. > > I don’t believe there are any copper cables carrying civilian undersea voice or data traffic at this point. In the not-too-distant past, there were still some being used for other purposes. > > You can send data in both directions simultaneously on both copper and fiber. There were a number of different methods to do this on copper. For a good read on the older systems, I recommend “Transmission Systems for Telecommunications” from Bell Labs (1959). > > On fiber optic cables, the normal method is to use different frequencies of light (search for CWDM or DWDM). This equipment used to be quite expensive and would only be used when the cost of the fiber link was even more expensive, but the cost has come way down. You can get equipment to multiplex 8 to 12 signals over a single fiber for under $1000 now. You can get a SFP transciever for Gigabit Ethernet that carries a link over a single fiber for around $40 (search for “1000BASE-BX10”). > > Back on the original topic - the Germans were able to decrypt the simple encryption (A-3 scrambler) used on the earlier Churchill / Roosevelt radiotelephone calls. They simply set up a radio listening station on the Dutch coast and eavesdropped. > > The solution was a SIGSALY (“Green Hornet”) encrypt/decrypt device. [Reference](http://cwr.iwm.org.uk/server/show/ConWebDoc.5795) > > For more info, I suggest “National Service in War and Peace (1925–1975)” which is also a Bell Labs book. I interviewed at a cable landing station in California. One interesting benefit of increasing bandwidth and dropping costs was the equipment footprint decreasing in size. When they showed me the actual equipment area, I was told that they’d populated 3/4’s of the space with room for expansion. And expand they did–except with all the upgrades, the space occupied by the equipment was now a 1/4 of the original footprint. Moore’s Law at work. ---
**Author:** ![Terry\_Kennedy](https://avatars.discourse-cdn.com/v4/letter/t/c57346/32.png) [@Terry\_Kennedy](https://boards.straightdope.com/u/Terry_Kennedy)\ **Post date:** [June 7, 2011, 8:33pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/45 "2011-06-07T20:33:21Z")
> [@user\_hostile](#): > > I interviewed at a cable landing station in California. One interesting benefit of increasing bandwidth and dropping costs was the equipment footprint decreasing in size. When they showed me the actual equipment area, I was told that they’d populated 3/4’s of the space with room for expansion. And expand they did–except with all the upgrades, the space occupied by the equipment was now a 1/4 of the original footprint. The same is true of the switching equipment - older central offices built for 1A ESS or older switches have needed far less floor space even as the number of customers increased, due to replacing the switches with newer, more compact ones. Many COs have entire floors that are vacant except for some power distribution and ventilation systems. In some cases, those are rented out, either by-the-rack to other carriers, or whole floors are rented out to customers who appreciate the “built like a battleship” characteristics of telco CO buildings. ---
**Author:** ![whitetho](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whitetho/32/1059_2.png) [@whitetho](https://boards.straightdope.com/u/whitetho)\ **Post date:** [June 7, 2011, 11:13pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/46 "2011-06-07T23:13:10Z")
> [@focusoninfinity](#): > > Page 245, “_David Sarnoff_”, a biography, by Eugene Lyons, Harper & Row, 1966. > > "The suspicion that underseas cables could be tapped by an enemy was not born in Sarnoff’s mind. It had been raised by electronics experts as far back as 1920 but somehow had failed to register in the military establishment. Once aware of the possibly, however, Sarnoff never forgot it. Meanwhile the refinement of electronic powers tended to raise the suspicion to a near certainty. > > "The Atlantic was swarming with German submarines. The geographical pattern of ship stinkings showed the enemy hunted close to transocean cable. Why, then, did he refrain from cutting the cables, as the Germans had done promptly in World War I and were expected by the Allies to in the new war? Colonel Sarnoff’s answer was simple and starling–President Roosevelt, who was briefed on the subject, was among those startled. > > "_If Hitler’s U-boats were siphoning off valuable information by tapping and_ _decoding cable messages,_ Sarnoff pointed out, _they would scarcely wish to interrupt their flow…"._ > > This via a once 12-4 Watch, Navy Research Lab’s, _ **USNS Mizar** _, **T-AGOR 11** , O/S helmsman, on the lee side of life. This would hardly be the first time that David Sarnoff rewrote history, but I can’t find any evidence that Germany actually cut any cables during World War One. In fact, the reverse was true, and it appears that the Allies cut, and often rerouted, all the German cables. My source is “Cables and Wireless” by George Abel Schreiner, written in 1924. In reviewing the Great War, it notes that at the start of hostilities there were two undersea cables that ran from Germany to New York. For one cable, which came under the control of the British, the western end was cut and rerouted to Halifax, while the eastern end was rerouted to Pendance, England. The second cable, which came under French control, remained connected to New York, but the eastern end was moved to Brest, France. A third cable ran from Germany to Liberia – that one was rerouted to run from France to Dakar. There were also a number of smaller lines, with the ones in the Pacific seized by Japan. I don’t see any references in this book to any Allied lines being disturbed. ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [June 13, 2011, 1:35pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/47 "2011-06-13T13:35:31Z")
> [@constanze](#): > > Actually, no. Cable companies want to lay the shortest route, true. But for ships, even with engines, the longer route may be the quicker one, due to wind or current. And your explanation for the maps I posted is…? ---
**Author:** ![jaguizzetti13](https://avatars.discourse-cdn.com/v4/letter/j/5daacb/32.png) [@jaguizzetti13](https://boards.straightdope.com/u/jaguizzetti13)\ **Post date:** [August 11, 2011, 2:10pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/48 "2011-08-11T14:10:39Z")
I couldn’t tell if anyone else answered with what I’m about to say. So many posts. It was most definately possible to cut the transatlantic cables and intercept them as the british had done so during WWI against the germans to intercept the telegrams. Ever heard of the Zimmermann telegram? It’s one of the biggest reasons the US was finally drawn into the war. I wouldn’t be surprised if Hitler did it as well, by which time it was the 1930s and WWI began in 1914. The English declared war and cut the cables on August 4th of that year. The technique they used was sailing out to the points where the cables lay, throw large metal hooks into the ocean and fish them out, and then cut them. The british later returned to stop possible repairs and pulled the broken end back to their land, away from the germans. Like I said, I don’t know if Hitler did the same thing, but it was possible. ---
**Author:** ![jaguizzetti13](https://avatars.discourse-cdn.com/v4/letter/j/5daacb/32.png) [@jaguizzetti13](https://boards.straightdope.com/u/jaguizzetti13)\ **Post date:** [August 11, 2011, 2:16pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/49 "2011-08-11T14:16:23Z")
> [@whitetho](#): > > This would hardly be the first time that David Sarnoff rewrote history, but I can’t find any evidence that Germany actually cut any cables during World War One. In fact, the reverse was true, and it appears that the Allies cut, and often rerouted, all the German cables. > > My source is “Cables and Wireless” by George Abel Schreiner, written in 1924. In reviewing the Great War, it notes that at the start of hostilities there were two undersea cables that ran from Germany to New York. For one cable, which came under the control of the British, the western end was cut and rerouted to Halifax, while the eastern end was rerouted to Pendance, England. The second cable, which came under French control, remained connected to New York, but the eastern end was moved to Brest, France. > > A third cable ran from Germany to Liberia – that one was rerouted to run from France to Dakar. There were also a number of smaller lines, with the ones in the Pacific seized by Japan. I don’t see any references in this book to any Allied lines being disturbed. Hitler was during world war two, not one, as the first war ended in 1918. And Hitler was the second war, not first. He was however, climbing the ranks in the first war which helped him start the second. ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [August 11, 2011, 3:25pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/50 "2011-08-11T15:25:22Z")
> [@jaguizzetti13](#): > > I couldn’t tell if anyone else answered with what I’m about to say. So many posts. > > It was most definately possible to cut the transatlantic cables and intercept them > > as the british had done so during WWI against the germans to intercept the telegrams. > > Ever heard of the Zimmermann telegram? It’s one of the biggest reasons the US > > was finally drawn into the war. I wouldn’t be surprised if Hitler did it as well, by which time it was the 1930s and WWI began in 1914. The English declared war and cut the cables on August 4th of that year. > > The technique they used was sailing out to the points where the cables lay, throw large metal hooks into the ocean and fish them out, and then cut them. The british later returned to stop possible repairs and pulled the broken end back to their land, away from the germans. > > Like I said, I don’t know if Hitler did the same thing, but it was possible. As far as I can tell, almost none of this is correct. The British cut the German cables to the US in WWI, but did not move or intercept anything on the cut cable. The Germans were forced to send their cable on one that passed through England, disguising it as originating from Sweden in the hopes England wouldn’t read it. But they did anyway. [That’s what Wiki says](http://en.wikipedia.org/wiki/Zimmermann_Telegram), anyway. Here is a more complete version, an excerpt from _The Code Book_ by Simon Singh: > [@](#): > > Before dawn on the first day of the First World War, the British ship Telconia approached the German coast under cover of darkness, dropped anchor, and hauled up a clutch of undersea cables. These were Germany’s transatlantic cables - its communication links to the rest of the world. By the time the sun had risen, they had been severed. This act of sabotage was aimed at destroying Germany’s most secure means of communication, thereby forcing German messages to be sent via insecure radio links or via cables owned by other countries. Zimmermann was forced to send his encrypted telegram via Sweden and, as a back-up, via the more direct American owned cable. Both routes touched England, which meant that the text of the Zimmermann telegram, as it would become known, soon fell into British hands. ---
**Author:** ![obbn](https://avatars.discourse-cdn.com/v4/letter/o/d6d6ee/32.png) [@obbn](https://boards.straightdope.com/u/obbn)\ **Post date:** [August 11, 2011, 11:13pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/51 "2011-08-11T23:13:44Z")
> [@alexphobos](#): > > However, tapping would require a boat or submarine to stay “on site” permanently to monitor transmissions, even if it were able to pick them up. While the majority of your post is correct, the above statement not so much. If, and that is a big if, the Germans were able to “snag” the cable they would only have to splice into the cable with one of their own. Run that cable back to land or remote spot and listen from that location. It would not require the ship or sub to constantly be at the cable. However, in practicallity this would be pretty tough to do. Not to mention the cable that runs the sea bed is not a single pair cable, but a cable with thousands of of pairs in it. Meaning that while it is possible to splice on an extension to every individual pair you would have to have some way to monitor all of the thousands of pairs and then deduce which converstation is the one that you need to listen to. In this era of computers, it is a realatively simple task to do. However (and my knowledge of 1940 telephone tech is limited) I don’t think there would be a practical way to do this. Also, as a telephone tech if I were looking for a “tap” on a line I would hook up a meter to the line and look for a drop in voltage indicating another source (telephone set) was on the line. Surely this could be detected by the technology they had available then. ---
**Author:** ![Kiwi\_Fruit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kiwi_fruit/32/12_2.png) [@Kiwi\_Fruit](https://boards.straightdope.com/u/Kiwi_Fruit)\ **Post date:** [August 12, 2011, 12:04am UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/52 "2011-08-12T00:04:31Z")
> [@obbn](#): > > While the majority of your post is correct, the above statement not so much. If, and that is a big if, the Germans were able to “snag” the cable they would only have to splice into the cable with one of their own. Run that cable back to land or remote spot and listen from that location. It would not require the ship or sub to constantly be at the cable. > However, in practicallity this would be pretty tough to do. Not to mention the cable that runs the sea bed is not a single pair cable, but a cable with thousands of of pairs in it. Meaning that while it is possible to splice on an extension to every individual pair you would have to have some way to monitor all of the thousands of pairs and then deduce which converstation is the one that you need to listen to. In this era of computers, it is a realatively simple task to do. However (and my knowledge of 1940 telephone tech is limited) I don’t think there would be a practical way to do this. > Also, as a telephone tech if I were looking for a “tap” on a line I would hook up a meter to the line and look for a drop in voltage indicating another source (telephone set) was on the line. Surely this could be detected by the technology they had available then. I believe your response is incorrect too. As discussed earlier in the thread, the trans-Altlantic cables during the period were telegraph only. Telephony wasn’t introduced until later. The telegraph cables were commonly 1 wire with armour sheathing. Telegraphy could use duplex sending (both directions at once) and could also have a bridge to derive more than one circuit each way. The idea of tapping the cable to detect the transmissions wasn’t as simple as clipping on your receiver though. Because of the immense inductance and capacitance invovled with a 3 thousand mile cable, there was very special circuitry to condition the cable. Any attempt to tap into the cable would require extremely careful work to avoid being detected by the fact of the cable no longer working! ---
**Author:** ![R.N.Thomas](https://avatars.discourse-cdn.com/v4/letter/r/2acd7d/32.png) [@R.N.Thomas](https://boards.straightdope.com/u/R.N.Thomas)\ **Post date:** [December 19, 2011, 5:38pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/53 "2011-12-19T17:38:03Z")
He did listen in but it was a HF Radio telephone with scrambler. If the subject really interests you read David Kahn’s The Code Breakers. ---
**Author:** ![General\_Apathy](https://avatars.discourse-cdn.com/v4/letter/g/7ab992/32.png) [@General\_Apathy](https://boards.straightdope.com/u/General_Apathy)\ **Post date:** [January 16, 2016, 7:11pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/54 "2016-01-16T19:11:32Z")
See “Intercepted conversations - Bell Labs A-3 Speech scrambler and German codebreakers” @ [Christos military and intelligence corner: Intercepted conversations - Bell Labs A-3 Speech scrambler and German codebreakers](http://chris-intel-corner.blogspot.com/2012/02/intercepted-conversations-bell-labs-3.html) A-3 was an analog system that by 1943 was replaced by SIGSALY, which transformed voice signals into digital data which could then be reconstructed (or synthesized) into intelligible voice. It was called a “vocoder,” short for voice coder. More details in the NSA historical publication “Sigsaly - The Start of the Digital Revolution” by J. V. Boone and R. R. Peterson @ [National Security Agency | About NSA Mission](https://www.nsa.gov/about/cryptologic_heritage/center_crypt_history/publications/sigsaly_start_digital.shtml) ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [January 17, 2016, 7:50am UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/55 "2016-01-17T07:50:16Z")
[QUOTE=jaguizzetti13;14126610 Like I said, I don’t know if Hitler did the same thing, but it was possible.[/QUOTE] sure, but for for WW II, it wasn’t possible for the Axis to do it, 1. You do it close to land , which means at sea but not strictly “in the ocean”. 2. You don’t do it with submarines. One, the weakness of the cables was known, and so they were protected across their route in the shallows. two, the cut would alert the British Navy as to the exact location of a submarine (timing the echo down the line tells you how far down the line the cut is !) , who would likely have a plane dropping depth charges right on the spot. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [January 17, 2016, 10:25am UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/56 "2016-01-17T10:25:44Z")
This may be of interest: Ruth Ives was employed as a censor "_“I pushed open the door of a very bombed out building in St Martins Le Grand called Union House… I was met by a very fierce colonel who was not used to having female staff around him. He told me that because I had verbatim shorthand and my security record was good, I was going to censor the calls on the transatlantic radio telephone line.”_ > [@](#): > > “Even they were very amused to be called Mr White [Churchill] and Mr Smith [Roosevelt]. I thought even the dumbest German would be able to recognise their voices! And they didn’t keep it up for very long. Especially when Mr Smith asked Mr White how is the colonel? I thought which colonel? But the colonel was Mrs Churchill. The President always asked after Mrs White.” > > [BBC - London - History - Listening in on Churchill](http://www.bbc.co.uk/london/content/articles/2008/09/01/ruth_ive_feature.shtml) ---
**Author:** ![General\_Apathy](https://avatars.discourse-cdn.com/v4/letter/g/7ab992/32.png) [@General\_Apathy](https://boards.straightdope.com/u/General_Apathy)\ **Post date:** [January 17, 2016, 3:47pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/57 "2016-01-17T15:47:11Z")
See TICOM I-190 ’Extracts from report on interrogation of Dr Hans Wilhelm Thost’ [Ticom I-190 Thost | PDF](http://www.scribd.com/doc/254443036/Ticom-I-190-Thost) Dr. Thost was one of the employees of the Sicherheitsdienst who translated incoming A-3 material. Scroll down to the second and more legible copies of the report - there is also additional material of a similar nature at the bottom of the page. ---
**Author:** ![General\_Apathy](https://avatars.discourse-cdn.com/v4/letter/g/7ab992/32.png) [@General\_Apathy](https://boards.straightdope.com/u/General_Apathy)\ **Post date:** [January 17, 2016, 5:00pm UTC](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099/58 "2016-01-17T17:00:02Z")
For what it might be worth there were no Trans-Atlantic _telephone_ cables before 1956 [TAT-1 - Wikipedia](https://en.wikipedia.org/wiki/TAT-1) [Previous page](https://boards.straightdope.com/t/did-the-germans-tap-transatlantic-phone-cables-in-wwii/220099.md?page=2)