Double Cross – Britain’s Double Agents in World War II
When World War II began, the United Kingdom was rightly worried about German spies in their midst. Britain’s MI5 (Military Intelligence, Section 5) was tasked with counterespionage–to find and capture enemy agents before they could send dangerous information to Germany. Although capturing and executing these spies made the nation feel more secure and sent a message to Germany, MI5 decided many of these agents might be more useful alive than dead.
58 St. James’s Street, London, site of MI5’s London Headquarters in World War II (Photo: Sarah Sundin, 9 May 2024)
In September 1940, MI5 began the “Double Cross” program, to “turn” enemy agents to become double agents. The ideal double agent would send messages to Germany using his German radio and codes or via letters written in secret ink to addresses in neutral countries – but these messages were provided by MI5. At first a new double agent sent “chicken feed,” containing information that was true and verifiable, but not harmful to the British war effort. Since Germany could purchase British newspapers in neutral Portugal and could verify certain facts by aerial reconnaissance, relating truthful information built trust in the eyes of the agent’s German handlers.
As the war progressed, MI5 even allowed their double agents to commit fake sabotage, blowing up buildings of no importance at vital locations. Since the local authorities and the press weren’t aware of what was actually happening, reports of suspected sabotage in the newspapers and aerial photos of the damage further built up the agents’ reputations in German eyes.
The more the German Abwehr trusted their agents, the more these agents were able to participate in strategic deception, feeding blatantly false information to deceive the Germans about Allied military plans. This reached its culmination on D-day, when an intricate web of deception, including messages from the most trusted double agents, convinced Germany that the Allies would land in the Pas de Calais region of France rather than Normandy. “Knowing” this, Hitler refused to release reinforcements for several weeks after D-day, saving countless Allied lives.
German Abwehr SE88/5 spy radio (Photo: Crypto Museum)
One of the reasons the Double Cross program was so successful was because MI5 knew the Abwehr did indeed trust their agents. Because the Abwehr transmitted reports from their agents in Britain verbatim over the radio, codebreakers at Britain’s Bletchley Park were able to break the Abwehr code on December 8, 1941. Reading Abwehr radio traffic showed Mi5 which agents were trusted and which weren’t, which messages were believed and which weren’t, and – this was as shocking then as it is now – every single German agent sent to British soil was “in harness” – either in prison or working as a double agent.
It is believed only one Abwehr agent escaped capture during World War II—and he didn’t have a working wireless transmitter and committed suicide. Of the German agents captured throughout the war, sixteen were executed, but about three dozen were turned to become double agents.
With a great deal of ingenuity and organization, Britain’s MI5 was able to take one of their greatest fears and turn it into one of their greatest assets.
Thanks for running this giveaway; paperbacks are the best (no blue light involved when reading them)!
I like them best too!
Love all the research you have done regarding MI5 and the German Double Agents! Midnight on the Scottish Shore is now on my TBR!
Thank you, Julie!
Thank you for the giveaway. I love reading paperbacks.
Thank you, Deborah!
Midnight on the Scottish Shore was great. The characters were believable, and the interactions and development were very good.
Thank you, Beth! I’m glad you liked the story!
I love historical books
Me too!
Excited to discover you as a new author to me!
Thank you, Danielle! I’m glad you stopped by!
I believe I just subscribed to your newsletter. Looking forward to this latest book. Spies are so fun!
Thank you so much, Megan!
Thank you for being a part of this scavenger hunt. I already own Embers in the London Sky and Midnight on the Scottish Shore. I love your books, I have several.
Thank you, Kathy! I’m glad you’re enjoying them!
Love spy novels. Can’t wait to read one of your books.
Thank you, Sarah!
Sarah, what a wonderful article! I always learn so much when I visit your site or read your books. I would love to win one of the two-packs in this giveaway. Happy writing!
Thank you so much, Andrea!
Sarah,
You are my favorite author!
Thank you so much, Jill!
Wooo! This one sounds really interesting. I love WWII and historical fiction and I feel like you never really can learn everything about WWII. I really hope I win your book! If not, I definitely need to check my local library or put in a purchase request.
Thank you, Maria! I hope you enjoy the story!
I love reading all the historical tidbits you share. It really helps the books come alive for me!
Thank you, Shannon! I’m glad you enjoy them!
My first comment may be lost to poor connection. I apologize if this is a duplicate.
I’m writing this morning at my local library and grabbed a copy of Embers in the London Sky. I was hooked with the first page and can’t wait to read the rest. WWII is dear to my heart from stories my mom told of her life during it as a young woman and her brother’s service in the Pacific arena. I’ve thought of a few story ideas set in that time so am praying for inspiration from your writing. Thank you!
Thank you, Karen! I’m glad you’re enjoying Embers in the London Sky!
I’m so glad to get to meet some new authors. I am an avid reader and always read every book an author I like puts out there and I’m running out of authors.
Thanks, Christy! That’s what makes the scavenger hunt so fun!
I’ve enjoyed every book of yours that I’ve read. Probably because of the research you’ve obviously done before writing the stories. Some I have in my own library, but most probably have been borrowed from the library. I’ve love to add these to my own library.
I just read recently a book [His Majesty’s Hope by Sara Elia MacNeal] that mentioned the “Double Cross” program. Now I want to read and know more about it.
Thank you, Donna! It’s a fascinating subject!
Love all of Sarah’s books. Have not yet read the two being offered in this giveaway.
Thanks, Anne-Marie! I’m glad you’re enjoying the stories!
Those books looks so much a want to read.
Thank you, Theresa!
Sarah, I really enjoyed Midnight on the Scottish Shore. Thanks for participating in this scavenger hunt.
Thank you so much, Denise!
Sarah,
I always look forward to and enjoy each of your new novels. Your research is impeccable, and your stories are realistic, informative, and filled with emotion. All these elements, plus romance and mystery, make for excellent reading!
Thank you so much, Lisa! I’m glad you enjoy them!
I enjoy reading stories about WW 11. I appreciate the time you take checking for authenticity in your books.
Thank you, Shirley!
Thank you for sharing interesting info. Love your books.
Thank you, Deana!
Loved Midnight on the Scottish Shore! Will there be another book – Gerrit, perhaps?
Yes! Gerrit’s story is coming February 2026. He’s going to Jersey in the German-occupied Channel Islands, where he meets Dr. Ivy Picot… More info coming soon…
I love all your books that I have read. Really looking forward to reading this one as well!
Thank you, Sharon! I’m glad you’re enjoying the stories!
Who doesn’t enjoy a scavenger hunt. Thanks for sharing the historical info. Thanks for participating!
You’re welcome! Thanks for dropping by!
I love all the history you weave into your stories! I love your books.
Thank you, Brandi! I’m glad you’re enjoying them!
I love reading your books! Thanks for sharing the information about the double agents – how interesting!
Thank you, Shelley! I’m glad you enjoyed it!
I love Historical fiction. Thank you for the chance.
Thanks, Alicia!