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On this page you can find a set of mostly complete and authentic U-boat M4 Enigma procedures as they were formulated and used in WWII.  These "M4 Advanced" procedures are intended for those EWCG members who have already mastered the "M4 Basic" procedures and are looking for an even greater challenge.  We hope that you are as excited as we are for these additions to the EWCG site. 

The list below links you to a series of documents that are translated procedures. You should read the "Enigma General Procedure" first, followed by "Quick Reference Guide for M4." This will get you started. Below the first list are links to folders on the DropBox that will get you the files you need. Note that the 2019 Link reads M3/M4. That is because the Kriegsmarine continued to use the M3 version of the Enigma through the end of the war on surface ships, shore artillery, etc. The M4 was the primary cipher machine starting in 1942 and was exclusively used by the U-Boot fleet. To that end, I have added code sheets for the NEPTUN radio net, which was the Kriegsmarine surface ship radio net and used the M3 Enigma machine.

As always, if you have questions and need assistance, drop me an email at

To print these documents:

  1. Click on document title.

  2. Click on "download."

  3. Click on "direct download."

  4. Once document is open, click to print.

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