[A table for cracking Vigenere ciphers.]

Cryptography is probably the only puzzly skill in history upon which lives have depended. The movements of troops, plans for invasion, locations of key officers, spies, and personnel… all of these vital pieces of information have been encoded numerous times across numerous conflicts, all in the hopes of keeping that data from prying eyes.

It’s not as if anyone has to solve a crossword to prevent a Dennis Hopper-esque madman from wreaking havoc on Los Angeles, or the outcome of a pivotal battle hinged on someone finding all the words in a word seek faster than the enemy.

But cryptography is both a delightful diversion and deadly serious, depending on the context.

Which makes it all the more curious that it took more than a hundred years for a Confederate message from the Civil War to be decoded.

The coded message was first displayed in The Museum of the Confederacy in Richmond, Virginia in 1896, after being donated by Captain William A. Smith, a member of Walker’s Greyhounds, a division of Texans fighting for the Confederacy.

The actual message was unknown. The rolled-up slip of paper was tied with a linen thread and placed in a small glass vial along with a .36-caliber lead pistol bullet, and stoppered shut. (The bullet was included in order to make the vial heavy enough to be tossed into the river and sink if the scout carrying it was in danger of being captured.)

The mysterious message was meant for General John C. Pemberton, the Confederate general attempting to protect and defend Vicksburg from the army of Union Major General Ulysses S Grant. The same general who would surrender Vicksburg to Grant on July 4, 1863 after 47 days under siege.

But the message never got to Pemberton. Instead, it ended up as part of a Civil War museum, its message undelivered, its code unbroken.

Until 2008, when curiosity among museum staff led to an unveiling a century later than intended. The message was photographed and then returned to the glass vial, which itself was then returned to its display.

And the message intended for General Pemberton?

SEAN WIEUIIZH DTG CNP LBNXGK OZ BJQB FEQT FEQT XZBW JJOA TK FHR TPZWK PBW RYSQ VOWPZXGG OEPF EK UASFKIPW PLVO JKZ HMN NVAEUD XYE DWRJ BOYPA SX MLV FYYRDE LVPL MEYSIN XY FQEO NPK M OBPC FYXJFHOHT AS ETOV B OCAJDSVQU M ZTZV TPJY DAW FQTI WTTJ J DQGOAIA FLWHTXTI QMTR SEA LVLFLXFO.

Unlike many simple coding techniques, this is not a Caesar cipher where each letter is simply another letter of the alphabet in disguise. (Every E is actually an L, every F an M, etc.)

This is a Vigenere cipher, where a key word or phrase is required to unlock the letter substitution involved. For centuries, this cipher was considered unbreakable, though this was no longer the case by the time of the Civil War. (The Union regularly cracked coded Confederate messages.)

By 2008, Vigenere ciphers were easily cracked by amateur and professional cryptographers alike, and the Confederate message was finally revealed to the world:

Gen’l Pemberton, you can expect no help from this side of the river. Let Gen’l Johnston know, if possible, when you can attack the same point on the enemy’s line. Inform me also and I will endeavor to make a diversion. I have sent some caps. I subjoin despatch from Gen. Johnston.

Essentially, the message means that the reinforcements Pemberton was hoping for to shore up Vicksburg’s defenses weren’t coming.

But the message never got to the general, because before the scout arrived with the bad news, Vicksburg had already fallen, and Pemberton had surrendered.

So instead, the scout, having somehow realized from afar that Vicksburg was lost, returned to his camp and handed the unopened message to a Captain Smith, the same man who would later donate the message to the Museum.

And an enduring mystery was born.

[I learned of this story in the book Hidden Treasures: What Museums Can’t or Won’t Show You by Harriet Baskas, which also inspired my post a few weeks ago about the Morris Museum music box.]

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