Agent Knopf

A Polish Spy in Hitler's High Command

Apr 02, 2025

Polish contributions to the Allied war effort have rarely received as much attention as they deserve. For instance, the mathematician Marian Rejewski’s breaking of the early Enigma cryptography system and his donation of his discovery to Bletchley Park are invariably overshadowed by the wartime achievements of Bletchley Park itself.

Then there are the extraordinary adventures and mad courage of Underground couriers like Jan Karski, who smuggled himself into a German death camp, infiltrated the Warsaw Ghetto, and sneaked key information on, and photographs of, the ongoing Holocaust to disbelieving British and American authorities.

Even less well-known are the activities of Agent Knopf, which were uncovered only in 2011 by the British academic, Paul Winter (who has a Substack). Knopf appears to have served in OKH (Oberkommando des Heeres), or Army High Command. For more than a year (1942-43) he seems to have supplied his contacts in Polish Intelligence (and thence the Polish government-in-exile in London) with high-grade intelligence on planned German operations in the Mediterranean and the USSR.

I say “appears” and “seems” because there is so much about him that remains mysterious. And, spoiler alert: No, I’m not going to reveal his True Identity, as no one knows who he was, his fate, or his motivations. As far as is known, his reports stopped sometime in the spring of 1943, indicating that he was caught and executed. Or maybe he just quit out of fear or was killed after being posted to the Eastern Front. At this late date, unfortunately, I can’t imagine we’ll ever find out.

Still, his achievements stand on their own merits, and while documentation is patchy there is enough that survives to tell an intriguing, if partial, story.

JX/Knopf

British military intelligence (MI14) first heard of “JX/Knopf”—“JX” designated information derived from Polish-run sources—in mid-January 1942, when they received a report that Hitler was planning to “neutralise” but not “occupy” the strategically key island of Malta, which dominated the supply lines across the Mediterranean to Axis forces in North Africa. Not much attention was paid, however, to this vague warning until late March when two more detailed reports were received, this time stating that German High Command had firmly decided upon the “liquidation” of Malta.

Knopf claimed that, beginning in April, German and Italian bombers would soften up the island’s defenses, after which would come an amphibious invasion and paratroop drops to capture inland targets. Hitler, said the agent, was confident that British morale would soon collapse. Once done, Knopf asserted, General Rommel’s offensive against the British 8th Army in North Africa would commence.

Upon receiving all this, the Secret Intelligence Service (SIS) closely analyzed the JX/Knopf information. “The source, of whom the Poles think very highly,” it concluded, “is not himself a Pole. He has not specified his informants, but states that they are highly placed and in touch with the German High Command.”

The big question for SIS was whether to trust the veracity of Knopf. It was a sensible precaution. A year earlier, they had been burned by Agent Warlock, an allegedly senior source with a much cooler covername at OKW (Oberkommando der Wehrmacht, Armed Forces High Command). In 1940, his intelligence on German planning had been counted as premium, but by mid-1941 he was reporting banalities dressed up as revelations. It was almost as if he was telling SIS what he thought it wanted to hear.

Once his material was cross-referenced against the Ultra decrypts of Enigma intercepts, which contradicted everything he was saying, the British realized Warlock had been caught and turned into a double agent to feed them misinformation. Knopf could very well have been another Warlock.

With the benefit of hindsight, we can see that while Knopf had gotten certain things wrong—a Malta invasion was much more an Italian preoccupation than a German one; OKW, for one thing, was against it—what he had got right was tipping the British off to German intentions in North Africa some two or three months before they transpired.

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The Eastern Front

In the summer of 1942, then, Knopf was an interesting but not entirely verified source. But as time went on his intelligence on German planning and operations on the Eastern Front put him in the Pantheon. In April 1942, Hitler had ordered that in the coming campaign “the armies of Central sector will stand fast, those in the North will capture Leningrad … while those on the southern flank will break through into the Caucasus.” In other words, Stalingrad, the key to the Caucasian oilfields, was a prime target.

This Führer Directive was top secret, for obvious reasons, but Knopf began supplying information on the Army High Command’s war plan that soon began to pan out. What had at first sounded like forecasting and guesswork to skeptical analysts would turn out to be eerily accurate. Whoever he was, Knopf was somehow familiar with OKH thinking at the most senior levels. Given the security classification of these plans, there was no way that Knopf could be a Warlock-style double feeding back fake news, the Germans being well aware that the British would inform the Soviets of the coming operations.

In a series of ten reports, Knopf kept his Polish handlers and their British counterparts updated as to what was coming down the pike. On March 22, 1942, for example, he warned that “the main effort would be towards STALINGRAD, with a secondary attack towards ROSTOV.” A few months later, Knopf sent a detailed outline of German army reorganization in preparation for Operation Blau. Army Group South would divide into Army Groups A and B, with A seizing the Crimea and heading towards the Maykop-Grozny-Baku oilfields and B ordered to take Stalingrad before thrusting south to the Caucasus.

By the fall, Knopf was alerting his handlers that Hitler was obsessed with Stalingrad and capturing it “at all costs,” even going so far as to postpone the Leningrad operation and diverting divisions to beef up the South. And we all know what happened after that …

But then, from about the spring of 1943, the reports stopped, for reasons unknown.

Intermission

Let’s take a brief pause here so I can insert a plug for my own forthcoming (May 20, 2025—just in time for Father’s Day!) book, Phantom Fleet: The Hunt for Nazi Submarine U-505 and World War II’s Most Daring Heist, which is sure to dazzle and astound you (and your father).

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The Twist in the Tale

There’s a long debate in Classical studies over whether the “Homer” of the Iliad and Odyssey was one man or many. A similar one surrounds the identity of Knopf. He was always referred to by the Poles as a single person within OKH, and so did the British until the fall of 1942, when they began to suspect that Knopf might actually be a collective name for a group of agents and sources.

Before the War, the British had had a merry time reading weakly encrypted American diplomatic telegrams—this habit was stopped by Churchill as a goodwill measure to placate an unpleasantly surprised Roosevelt—but during it Bletchley Park had no compunction about intercepting Polish communications as a back-up measure.

It was by such means that in October 1942 they discovered the existence of a group the Poles dubbed “secret service agents No. 594.” Apparently, they too were penetration agents within OKH and they too supplied high-grade intelligence. Three days before the German attack on the Soviet Union in June 1941, for instance, they had warned of its imminence. And they later brought insider news of Hitler’s dismissal of several vacillating if competent German field marshals and generals before the battle of Stalingrad.

That the Poles had recruited not only Knopf but also a network of “secret service agents” within OKH was a remarkable feat, but it’s pretty much a dead cert that they were one and the same. It was, of all things, a report on Rommel’s health, marked by Polish Intelligence as “a confidential matter known only to O.K.W., and therefore cannot leak out anywhere,” that gave away the secret. The clincher was a single, distinctive phrase used by both Knopf and No. 594 in their respective reports: Rommel’s “faulty blood circulation caused by the African sun.” That’s too much of a coincidence to explain away.

There’s one more possible clue we can draw on. In his reports, Knopf sometimes misspelled or mangled names of German officers—a mistake that a genuine, highly placed agent at OKH would never make. A keen-eyed analyst at MI14 ascribed these slips to “errors in transmission,” meaning that Knopf was communicating with Polish Intelligence via scratchy radio rather than arranging face-to-face meetings.

I’m taking a stab in the dark here, but my guess is that “secret service agents No. 594” was a relatively lowly group of sources and sub-sources—maybe wireless clerks, messengers, or the like—whose various tips and gossip were collated, summarized, and sanitized by their Polish contact under the general covername of Knopf.

We’ll never know why they did it, but comments by Jan Karski, the Polish courier I mentioned at the beginning of this post, might possibly go some way towards providing an explanation. In his 1944 book, Story of a Secret State, Karski says on several occasions that he and other Poles used to bribe Gestapo men and even SS guards quite regularly to allow them into and out of forbidden areas.

So I wonder whether on-the-ground Polish Intelligence was paying for information from hard-up clerks at OKH who would be privy to a lot of sensitive messages. That at least one of them got careless and was caught sometime in the spring of 1943, or perhaps it was their contact, would explain why Agent Knopf suddenly vanished and was never seen again.