Declassified MI5 file shows Nazi spy almost changed course of war

A convoy of the supply ships travelling across the channel in 1939: a declassified file from MI5 has revealed a Nazi spy almost changed the course of the war

Michael Evans, Defence Editor

A Nazi spy came within days of uncovering one of the Allies' most important missions and possibly changing the direction of the Second World War.

The story of a Portuguese wireless operator and the dramatic decision to pluck him from his vessel on the high seas to prevent him from betraying the position of a huge convoy bound for North Africa is revealed for the first time in a declassified MI5 file released by the National Archives.

Gastao de Freitas Ferraz was being paid by German intelligence to send coded messages about convoys to U-boat commanders and was on the tail of the Allied warships.

The convoy included the USS Augusta, an American light cruiser that was carrying no less a person than General George S.Patton. General Patton was at that time in command of Operation Torch, the planned invasion of French North Africa, which was aimed at destroying the Axis forces fighting the British there and improving naval control of the Mediterranean.

Ferraz, who had been transmitting encrypted messages from his fishing boat, Gil Eannes, in the Atlantic, unwittingly had it in his power to sink the Allies' plans by reporting the size and direction of the convoy. But unknown to the Germans, the messages were being intercepted and deciphered by the codebreakers at Bletchley Park, Buckinghamshire. On August 9, 1942, MI5 was sent a “most secret” letter that referred to the “alleged unneutral behaviour” of a certain Portuguese wireless operator. Gil Eannes, a former Portuguese warship, was part of a large fleet authorised to operate in the Atlantic because of Portugal's neutrality. On June 28, 1942, it sailed out of Lisbon for Newfoundland and on its arrival there was searched. Nothing suspicious was found and neither Ferraz nor the other radio operator on board showed any sign of guilt. No orders were given at this stage to detain them because the only evidence about coded radio messages from the vessel was based on the most secret source of all - the Ultra material gleaned from the Enigma machines.

Sir David Petrie, the director-general of MI5, was personally involved in assessing the risk and on October 24 MI5 wrote to the Foreign Office: “There is no possible room for doubt that de Freitas is a German agent.” MI5 asked for Gil Eannes to be intercepted at sea: “You will, of course, appreciate that if any action is to be taken, it must be taken forthwith.”

With the fishing vessel getting closer to the Operation Torch convoy, the Foreign Office agreed, and the Admiralty sent out a secret signal to all relevant commands: “If the vessel is sighted West of 11 degrees West, she should be ordered not to use W/T [wireless transmission], de Freitas [Ferraz] should be removed and in order to ensure that no further use of W/T is made, an armed guard should be put on board.”

The warship HMS Duke of York duly intercepted Gil Eannes and Ferraz was detained and taken to Gibraltar. He was transferred to MI5's interrogation centre at Camp 020 in Ham, West London, where he confessed. After the war he was deported to Portugal.

Christopher Andrew, the official biographer of MI5, said: “Gastao de Freitas Ferraz was on the tail of Patton's troops and would have told the Germans where they were really going and could have affected the outcome of the whole war.”