In 1917, as World War I raged on, two officers named Harry Jones and Cedric Hill were being held captive in a remote POW camp in Turkey. There, Jones received a postcard from his aunt. She suggested he might pass the time practicing some form of spiritualism. She included precise instructions on constructing a Ouija board. Jones and Hill would soon be holding seances for the camp’s prisoners, a ritual that drew attention from the guards. Using coded information from home and their keen sense of human psychology, the two officers went on to cast a spell over their captors, a spell that would one day result in a daring escape. Here, we read about their first experiments manipulating the camp’s guards.
One April day, the Pimple—“the five-foot-nothing of impertinence”— sidled up to Jones. “You are a student of spiritism?” he asked cagily. “The sentries have told me. . . . Have you much studied the subject?”
“So-so,” Jones replied cautiously. He wondered whether he was going to be punished.
“I want you to answer by occultism for me some questions.”
Needing time to ponder this unprecedented demand by one of his captors, Jones asked the Pimple to join him in half an hour for tea in Upper House. “I walked back, up the steep path, thinking hard,” he recalled. “Hitherto spooking had been merely a jest, with a psychological flavouring to lend it interest. But now a serious element was being introduced. . . . Without any clear vision of the future, with nothing but the vaguest hope of ultimate success, I made up my mind to grip this man, and to wait for time to show how I might use him.”
At the prisoners’ spartan tea, the Pimple dropped off his list of questions. Every one of them centered on his romantic prospects: Though he possessed none of the requisite attributes, he fancied himself a Casanova. The questions were put to the board at the next séance, and the Spook obliged him with just the sort of assurances he was seeking. “The answers created a deep impression on Moïse . . . who, at this time, was not a believer in spiritualism,” Jones wrote. “He had only reached the stage of wondering if there might not be something in it. . . . I felt I had a difficult task in front of me and walked warily. I pretended an absolute indifference as to whether he believed in the Spook or not and never suggested that he should come to séances. The result was that he consulted the Spook once, twice and again. Every time, without knowing it, he gave something away. I privately tabulated his questions, studied them hard, and determined above all to hold my own counsel until the time was ripe.” 
Around this time, the Spook began issuing regular war news bulletins, obtained, Jones asserted, direct from the Beyond. A first-rate correspondent, the Spook reported authentic information about the progress of the war—intelligence forbidden to prisoners—including the ultimate seizure of Kut by the British in February 1917, and the fall of Baghdad the next month. The actual source of these reports was encrypted messages from prisoners’ families, for coded communications in both directions had been making their way between Britain and Yozgad since the captives first arrived. In August 1916, the Ottoman government had eased the restriction on letters. Writing home, prisoners were now allowed to fill both sides of a single sheet. But since mail to and from Yozgad was still vetted by Ottoman censors, the only way for the prisoners to get war news, and to relay accounts of their own condition, was in code. Jones once sent Mair a postcard that read this way:
Now Darllenwch: Send tea and tobacco, Eno’s, underclothes, needles, sugar, Antipon, tabloid ink, soap, Formamint, aspirin, cocoa, toffee, Oxo, razor, Yardley’s dental extract, matches, alum, nuts, dates, Euthymol, novels, quinine, uniform. I remain Yozgad for present.
The key word is “Darllenwch.” It looks like a term of endearment but is actually the Welsh imperative verb “Read!” And when the initial letters of the succeeding words are read together they spell “State unsatisfactory. Demand enquiry.”
In reply, Mair wrote:
Have sent parcels of following, Darllenwch dear: Grape-nuts, oil, Virol, Eno’s, razor, nuts, malt, elastic, novels, tea, envelopes, quinine, underclothes, ink, reels, indiarubber, needles, games. Eryl now growing long and noisy. Daisy very energetic. Ruth yesterday saw Ted. Rode over. Nesta going Newnham. Orme Willows empty now. Emma married. I expect spend Christmas Oxford. Llandudno after. Papa says I’ll never go. [Government enquiring. England very strong now. Enemies collapsing.]
To alert his family that a letter or postcard contained a code, Jones often addressed them curiously. Writing to his parents at their country home in Tighnabruaich, Scotland, he might mark the envelope “Tighnabruaich, Argyllshire, Scotland England,” an oddity that would slip past the censors but send an unmistakable signal to the Joneses.
He once sent his father a postcard whose text was entirely blank, with an address reading, “Sir Henry Jones, 184, Kings-road, Tighnabruaich, Scotland.” There was no such road in Tighnabruaich, and no such house number. Sir Henry, who had high government connections, brought the postcard to Room 40, the British Admiralty’s codebreaking department.  But as Room 40 labored away on the card, it was Mair who spotted its meaning: The address was a reference to the biblical Book of Kings, chapter 18, verse 4. The verse reads, “Obadiah took an hundred prophets and hid them by fifty in a cave and fed them with bread and water,” an indication that Jones and his fellows were being held at Yozgad with little to eat.
Prisoners also found covert means of requesting contraband. The Ottoman government had issued a long list of items that they coveted but were not allowed, including cameras, compasses, binoculars, non-safety razors, postage stamps, and currency. Sandes devised an ingenious way of asking his family for money, and an equally ingenious way of securing it on arrival:
I remember one occasion when Kiazim was superintending the opening of parcels of food and clothing which had arrived for us from England. I was among the lucky few who trooped up to his office to get the supplies sent by kind relations and friends. . . . We entered a room where Kiazim sat in state amid piles of parcels, while behind him hovered the interpreter Moïse. . . . Now, among the good things in one of the two parcels addressed to me I expected to find a tin of carbolic tooth-powder, and in that powder I hoped to discover several golden coins. I had sent a postcard to England asking for this tooth-powder, and had added that I had heard that it was much improved by the addition of certain yellow tabloids “which were made in two sizes only.”  Kneeling on the floor, I opened the first of my parcels beneath the watchful eyes of Kiazim himself. A tin of Huntley & Palmer’s fancy biscuits fell out, and behind it I spied a tin of carbolic tooth-powder. . . . It was a time for rapid action. If Kiazim handled the small tin and was surprised by its weight, I was lost. Hurriedly I opened the tin of biscuits. . . . Smiling, I offered it to Kiazim Bey, who saluted, selected a few biscuits, returned the remainder to me and at once turned his back, while I shoveled the contents of both parcels into a sack and left the office. He had his half-dozen biscuits and I my golden sovereigns.
Prisoners’ families also wrote in code. “The news that somebody’s father’s trousers had come down was . . . the occasion of a very merry evening,” Jones said, “for it meant that Dad’s Bags (or Baghdad) had fallen at last.  If, as occasionally happened, we found hidden meanings where none was intended, and captured Metz or Jerusalem long before such a possibility was dreamt of in England, it did more good than harm, for it kept our optimism alive.” Other messages from home told covertly “of Zeppelin raids, Lloyd George’s accession to the premiership,  Romania’s entry into the war and the fate of Russia’s lumbering armies.” Such items quickly found their way into the Spook’s dispatches.
In early May 1917, an extraordinary memorandum was posted in Yozgad. It forbade prisoners from conveying, in their letters home, “news obtained by officers in a spiritistic state.” The notice made Jones’s heart sing: He suspected it had been issued by Kiazim, and that Kiazim saw the spirit world as a force to be reckoned with. That scenario was plausible, as traditional belief was alive and well in the region. One summer night, the prisoners heard a prolonged firefight outside the camp—hundreds and hundreds of rounds. Yozgad was so remote it would scarcely have become a battleground. Could the gunfire be from the Russians, come to liberate them? No, they learned, it was only the townspeople responding to an eclipse of the moon. The shooting was designed “to scare away the devil who is obscuring her light.”
Wanting to confirm his suspicions, Jones took the Pimple aside:
“That’s a poor trick of yours,” said I, “stopping us writing home about spiritualism. We only want verification of what the Spook says. The matter is one of scientific interest. It has no military significance at all.”
“I say so to the Commandant,” said Moïse, “but he would not agree! He says it is dangerous.”
“Get along, Moïse! The Commandant has nothing to do with that notice. You put it up yourself to crab our amusements.”
Moïse probed excitedly in his pockets and produced a paper in Turkish which he flourished under my nose.
“There you are!” he said. “The seal! The signature! He wrote the order. I merely translated. I told him how great was the scientific value, how important is the experiment. He said the Spook gives war news. It is his fault, not mine.”
“Is the Commandant also a believer?” I asked.
“Assuredly! He has much studied the occult. He often consults[,] on problematic difficulties[,] . . . witches in this town, but mostly by cards. He greatly believes in cards.” . . .
As I went I hugged myself. The Commandant too! . . . How long, I wondered, would it be before I could get him into the net?
It was one thing to convert the Pimple. It would be quite another, Jones knew, to ensnare the remote, wary Kiazim—along with Kiazim’s chief henchman, the Cook, whose draconian hold on the camp belied his humble title. (“A limb of Satan,” O’Farrell called him. “He’ll poison or shoot you as soon as look at you.”) Jones realized he would need a lure so tantalizing that even Yozgad’s stoniest officials could not resist. He would not find it until September.
 In doing this, Jones had already, if unwittingly, adopted an essential trick of sham mediums. As Houdini wrote in his 1924 book debunking such charlatans: “One thing which makes the work of these mediums easier is the fact that many people tell things about themselves without realizing it. I have known people to deny emphatically that they had made certain statements or mentioned certain things in a seance although I had personally heard them say those very things not more than twenty minutes before. Under the excitement of the moment their subconscious mind speaks while their conscious mind forgets. This does not escape the medium who takes advantage of everything which it is possible to.”
 Established in October 1914, Room 40 would decipher the Zimmermann Telegram (the intercepted communication from the German Foreign Office urging a strategic alliance between Germany and Mexico) in January 1917. The decipherment was a major intelligence coup that helped bring about the United States’ entry into the war that April.
 I.e., sovereigns and half-sovereigns.
 Per the Oxford English Dictionary, “bags” as British slang for “trousers” is attested between 1853 and 1927.
 David Lloyd George served as the British prime minister from December 1916 to October 1922.
Excerpted from The Confidence Men: How Two Prisoners of War Engineered the Most Remarkable Escape in History, by Margalit Fox. Published by Random House. Reprinted with permission. Copyright 2021, Margalit Fox. All rights reserved.