I found this story on Futility Closet's blog here. It tells the story of the 1878 Treaty of Berlin and the journalist, Henri de Blowitz, who first leaked the top secret information to the press. Turns out he and his inside source had some international spy moves that are now seen as so cliche they're practically infantile. WELL, THEY WEREN'T IN 1878.
A picture of Henri de Blowitz:
Like Bond, but better. I hear that dangerous female honey-traps love a good whisker ticklin'.
ANYWAY, the Treaty of Berlin was a big deal because a whole bunch of world powers (the UK, Austria-Hungary, France, Germany, Italy, Russia, and the Ottoman Empire) got together and were like, "The fuck do we do with the Principality of Bulgaria? Is it independent, or what? SHUT UP, BULGARIA, YOU DON'T GET A VOTE." Their decision would have huge impact in Europe, and blah blah, this is the boring part, whatever.
Henri de Blowitz was like, "Scoop of the century! How do I get reliable information from these heavily guarded secret meetings?"
"Well before the congress started he had attached a confederate to the clerical staff, but the man felt he was being watched, so the two could not dare to meet or talk. Finally de Blowitz noticed that they wore hats of the same type and color, and he hit on a plan of 'childish simplicity.'
"De Blowitz was staying at the Kaiserhof. Each day his confederate went there for lunch and dinner. The two never acknowledged one another, but they hung their hats on neighboring pegs. At the end of the meal the confederate departed with de Blowitz’s hat, and de Blowitz innocently took the confederate’s. The communications were hidden in the hat’s lining.
"'Only twice were we forced to put off the communication till the following day,' de Blowitz wrote in his 1904 memoir. 'Once, however, we had a scare.'
"'One of my English colleagues, on leaving the dining-room, made a mistake and took my friend’s hat. Without looking at each other we felt, as he wrote me next day, that we turned pale. If the colleague in question had kept the hat, he might have discovered the third article of the treaty, which had been adopted at the previous day’s sitting, and also a hint of the difficulties that had arisen between Russia and England on the question of the boundaries of Bulgaria, and very disagreeable consequences for my friend might have been the result.
"'Fortunately, on reaching the door, the Englishman put on the hat, which dropped over on his nose. He laughingly took it off and replaced it on its peg. I had risen to take the hat from him, but sat down again. I breathed freely, and my friend must have done the same.'"
De Blowitz sent his information directly to the London Times, where it was published, much to the shock of those drafting the Treaty. De Blowitz refused to reveal his source for most of his life, but eventually cracked about 20 years later.
Moral of the story: Every top secret meeting/spy ring/private eye should have an elementary school child in attendance to check for plots that are so simple they fly under your radar.
Also, do better background checks on your clerks, International Committees.