Eberhard Maertens

Erhard Maertens or Eberhard Maertens (26 February 1891 – 5 May 1945) was a German Vizeadmiral of the Kriegsmarine during World War II. From 16 June 1941 to 5 May 1943, he was Chief of Office of Naval Intelligence, Naval War Command in the Oberkommando der Marine. Maertens was known for underestimating British intelligence, and specifically, overrating the security of the Naval Enigma cipher machine. In 1941, he held a naval enquiry into the strength of Naval Enigma security after the capture of U-boat U-570, and attributed all the suspicious losses in U-boats at the time to the British Huff-Duff. In the second enquiry, ordered by the Commander-in-Chief of the Navy Karl Dönitz, in May 1943, he investigated a number of areas, which exculpated Enigma security in the end, for the second time, incorrectly blaming British 9.7 centimetre centimetric radar for the massive losses in U-boats by mid 1943.

Naval career On 1 April 1910, Maertens joined the Imperial German Navy as a Seekadett and had basic training on the heavy cruiser until 31 March 1911. He was promoted to an officer candidate rank and sent to the German Imperial Naval Academy Naval Academy Mürwik for Naval training until 30 September 1912. and held in captivity until 5 November 1919.

That U-boat submariners, who were threatened with capture or destruction, did not destroyed the Enigma machinery or changed the configuration. That water-soluble ink would not work. That the enemy could detect the difference between the settings and those of the key list. That the British Admiralty could solve B-Dienst messages and extract the correct intelligence to enable the convoy to avoid the U-boats.

Maertens believed that these events were taken alone were unlikely, but when combined would be impossible. A bombing raid was ordered in an attempt to ensure that the U-13 and all associated Key M (i.e. Enigma cipher machine) infrastructures were destroyed. One of these investigations had been conducted by Kurt Fricke, Chief of Naval War Command, on another incident, the sinking of the German battleship Bismarck on 27 May 1941, caused great consternation in the Kriegsmarine, which resulted in a number of changes to Enigma cipher processes. On 18 October 1941, Maertens completed his analysis of the security consequences by stating in his report that "a current reading of our messages is not possible."

On the next page, however, he conceded that if the enemy had found the Enigma cipher machine untouched with all key documents, then a current reading was possible. The U-boats routinely carried between two and three months worth of daily key settings, so the enemy could have used U-570's material to read enciphered messages until November 1941. If these documents had fallen into enemy hands, the Maerten's results would be that "without doubt a weakening of the security of our cipher."

He concluded that having enough time to drench the documents would be unlikely, making their water-soluble ink unreadable. In the end, he left the impression that the British were not solving Enigma messages. In fact, once captured, a search of U-570 was conducted and useful papers had missed destruction, by the departed German crew. Copies of encrypted signals and their corresponding plain-language German texts were in fact discovered by the British. The U-570 papers included all supporting documentations for the Naval Key M ciphers.

Maertens's verdict in his final report had some very worrying conclusions:

We have to accept that the U-570 might have been captured by the enemy without anything having been destroyed. In these circumstances it cannot be ruled out that... a large amount of cipher documents are in enemy's hands. If this is true, the security of our enciphering procedure has been weakened... Out cipher will have been compromised if, as well as the enemy capturing the codebooks, our officers, who are now POW's have told the enemy the keyword, which since June 1941 has been given verbally to the U-boat commander so that he could alter the printed list of Enigma settings. If that has occurred, then we have to accept that our radio messages are being read by the enemy...The same would be true if the keyword had been written down in breach of regulations, and the codebooks and the keyword had fallen into enemy hands, or if, for example, the settings arrived at by the keyword order were written on the original settings list. If this happened, the enemy could work out the meaning of the keyword.

In fact, the Naval Intelligence Division had solved a message intercepted from U-111, and the Admiralty had dispatched the submarine to destroy the U-boats in the Bay of Tarrafal on the island of Santo Antão.

1943 Investigation In February and March 1943, Admiral Dönitz met with Adolf Hitler four times to discuss the Battle of the Atlantic, and the point that the Allies probably know the location of U-boat groups as they were routing the convoys around the U-boat packs. It was strongly suspected that the Allies broke the cipher machine, and again, Maertens was asked to conduct another enquiry. He again assured Dönitz and exculpated the Enigma cipher machine security.

In early May 1943, Maertens was fired by Dönitz for reasons that was beyond his fears about crypto-security and sent him to run the Kriegsmarine shipyard in Kiel.

Retirement and death Vice Admiral Erhard Maertens retired on 28 February 1945 from the service and died in May 1945 in Berlin.