The Cookbooks That Hid Coded Messages: How Recipes Became Espionage Tools in WWII

During World War II, espionage often conjured images of trench-coated figures meeting in shadowed alleys, coded telegrams, and whispers in dimly lit cafés. But some of the most ingenious intelligence work of the war didn’t take place in the shadows at all. It was baked, stirred, and scribbled into the pages of something utterly ordinary: cookbooks.

At first glance, these recipe collections seemed harmless, filled with instructions for stews, puddings, and frugal wartime meals. But for resistance networks and intelligence agents across occupied Europe, these cookbooks were far more than kitchen companions. They were camouflaged codebooks, hiding critical military information in plain sight.

Why Cookbooks Made the Perfect Cover

In wartime Europe, everyday objects became vital tools for survival and resistance. Cookbooks were especially clever as a cover for espionage because they were ubiquitous. Nearly every household, café, or safehouse had one. They could pass through checkpoints, be left on a kitchen table, or tucked into a suitcase without raising suspicion.

Food itself also made for a believable disguise. In an era of rationing, shortages, and inventive substitutions, unusual recipes drew little attention. If a recipe called for “two eggs” or “a pinch of salt,” no one would assume it meant “two aircraft” or “troop movement expected at dawn”—except for those who knew the code.

These coded cookbooks weren’t just a single network’s invention. Resistance cells in France, the Netherlands, and other occupied territories adapted the idea, using ingredients, quantities, and recipe order as ciphers. Some recipes even embedded geographical coordinates by referencing specific cooking times or oven temperatures, each linked to a pre-arranged key shared among operatives.

How the Recipes Worked as Codes

The methods varied, but many coded cookbooks relied on substitution ciphers disguised as cooking instructions. For example:

• Quantities carried meaning. “Two cups of sugar” might signal two units of ammunition or two convoys on the move.

• Ingredients stood for key terms. “Apples” might mean Allied forces, while “flour” could mean fuel.

• Cooking times or page order indicated locations or dates, especially when paired with known maps or timetables.

To an untrained reader, the recipe for “Apple Pudding” might seem like nothing more than a sweet treat. But for a resistance courier, it could translate into instructions to meet an agent near a specific supply drop or sabotage a railway on a given night.

Agents often memorised the cipher keys so the books themselves didn’t need to carry explicit instructions. If captured, the book alone would appear harmless, while the agent could still decode the message from memory.

Coded Cookbooks in the Resistance

This tactic became particularly valuable in occupied France and the Netherlands, where the Gestapo closely monitored mail, radio signals, and all forms of communication. Written letters often faced scrutiny, and radio transmissions risked detection. Cookbooks, on the other hand, slipped under the radar.

Some networks even created entirely fictional cookbooks—handwritten, designed to look domestic, but filled with recipes that doubled as orders or updates. These books were passed between couriers, sometimes under the guise of exchanging family recipes or sourcing substitutes for scarce ingredients.

The practice wasn’t without risk. If a pattern was discovered, the consequences were deadly. Resistance members caught with coded materials often faced torture or execution. For this reason, many cookbooks were burned or destroyed after the messages were delivered, leaving only a handful of surviving examples in museums and private collections today.

Other Domestic Codes: Knitting Patterns and Songbooks

Cookbooks weren’t the only domestic tools for subterfuge. Knitting patterns became another method for smuggling information, especially among women couriers. By dropping or purling stitches in a specific sequence, knitters could encode train schedules, supply routes, or coordinates into scarves or sweaters. These pieces could be mailed or carried without arousing suspicion, particularly because knitting was such a common pastime during the war.

Songbooks, too, occasionally doubled as codebooks, with specific verses, page numbers, or lines conveying hidden messages. Like cookbooks, these items travelled freely and were rarely scrutinised. Together, these covert tools demonstrated the creativity and ingenuity of ordinary people forced into extraordinary roles.

Fun Fact: The Ghost Recipes That Survive Today

Only a handful of original WWII coded cookbooks remain, many preserved in archives across Europe. In most cases, the ciphers have long been lost, but historians have pieced together how they worked by cross-referencing surviving code keys and testimonies from former agents.

One such example, a small Dutch recipe notebook, is held in a museum in Amsterdam. While it looks like a standard collection of home recipes, notes in the margins—numbers, arrows, and seemingly random ingredient swaps—reveal its true purpose as a communication tool for a local resistance group. Historians believe that at least a dozen sabotage missions were coordinated through this single, unassuming book.

These relics serve as reminders that, during the war, resistance wasn’t always about daring gunfights or dramatic escapes. Sometimes, it was as simple as writing down a “recipe” for stew.

Why These Domestic Codes Still Fascinate Us

The story of the coded cookbooks captures something remarkable about wartime resistance: the way ordinary, everyday life became a weapon. It wasn’t always spies in fedoras or secret radio stations. Sometimes, the most powerful tools were the ones no one would suspect—the things women and men already had in their homes.

These cookbooks, like the knitting patterns and songbooks that also carried secret messages, remind us that courage often hid behind the most mundane objects. They also highlight the ingenuity of those who fought oppression not with guns, but with creativity, subtlety, and a dash of everyday domesticity.

The next time you flip through a recipe book, consider that during WWII, such a book might have been far more than a kitchen companion. In the right hands, it could carry the fate of entire missions, whole resistance networks, and countless lives—all disguised as a guide to supper.