The US 6812 Division Bombe Report Eastcote 1944 Page 44

Tony Sale's Codes and Ciphers

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- 39 - TOP SECRET-T

D Uncle Walter. - Several varieties of Uncle Walter have been used with the
enigma machine. The A and B type were used during the Spanish Civil War. In
the summer of 1940 the German Air Force started using the C Uncle Walter and
then put it aside for the B. On 27 Dec 1944 we intercepted some clear text
asking if the other station had their U/W Dora. A new unknown U/W would
introduce 150 million,million possible combinations. However they did not
change to the new D U/W on 1 January as expected. But Norway was using the D
U/W with the same stecker board, wheel order and ringstellung as those using
the B board. As a result on 2 January we found the wiring of Uncle Dick. On
11 January some Norway messages didn't decode, which led to the conclusion
that Uncle Dick must be variable. Between 1 January and 1 March 7 different
wirings of Uncle Dick were encountered. In all of them B was always paired
with 0.

On 9 March the Russians captured the RED key, which forced the

Germans to use Uncle B for the rest of the month. A new call sign book came
out on 1 April. 3 different wirings of Uncle D were introduced on 9,21,30
April respectively. From the above experience it was assumed that Uncle Dick
was pluggable.

By 1 May the Germans were changing the stecker 3 times a day.

But they had to abandon this on 10 June because of so many operators errors.
There were no changes during June and July. In July we captured A RED key
sheet in Normandy which gave the U/W wiring for each 10 day period. This
verified the fact that Uncle Dick was pluggable.

If the use of Uncle Dick is continued, new decoding equipment

will have to be installed. Every 10 days it will be necessary to find another
of 150,0OO,OOO,O00,000 possible D wirings. It usually takes 5 of our
mathematicians about 2 weeks of hibernation to get the solution. The Giant
was developed for finding pluggable U/W's and takes 3 to 4 weeks to complete
a menu. The second Scheme adopted to solve the problem was to use a 4 wheel
machine with pluggable U/W. This took 16 days to complete a menu.

On 15 August the U.S. put out a 24-hour machine called DUENA.

(DUENA - U.S. Navy, AUTO SCRIPTER - U.S.Army, Arlington)

The D U/W is coming into frequent use on our machines. The

U/W wiring will be sent through from BP. Each wiring will be given a serial
number. Menus are received with the serial number to be used. The following
is the method of plugging the U/W extension to the bombe. There are three
jack rails on the extension and reading from left to right they refer to
Banks 3,2, and 1. The U/W wiring consists or 13 pairs of letters; for
example

A B C D etc
Y 0 L J


To plug this one end of a plug is inserted in "A" and the other end reversed
and plugged in "Y". Another plug is placed in "B" while the other end is
reversed and put in "O" and so on. All 3 banks are plugged in the same way..
Great care must be taken to insure that only one plug of the cord is upside
down and that all contacts on the plugs are straight, since it takes longer
to trace trouble on this than on ordinary patching.

In order to set up a checking machine for this type of menu there

should be a STRAIGHT drum in the 4th wheel position. The plug at the side of
machine must be removed. An EEL plug is inserted. This is plugged in the
same way as the U/W. With the ESL plug held upside down the connections are
then as follows;-


-------------------------
------------------------- Metal strip.
A C E G I K M O Q S U W Y
B D F H J L N P R T V X Z


To plug up, use the plugs provided to connect the letter required in the same


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