In earlier days of cryptology, handwriting was without question paramount to success – a person had to be able to read what was written, which meant the person on the other end also had to write legibly.

This would have applied to Commodore Isaac Chauncey and his staff, we suspect Chauncey, one of the great U. S. naval commanders of the early 1800s, was battled hardened after fighting the Barbary Pirates in the Mediterranean Sea for many years

Paul Hamilton, Third Secretary of the Navy

At the outset of the War of 1812, he was placed in charge of naval operations on Lakes Ontario and Erie, where he would be working in coordination with the U.S. Army against British and Canadian forces.  Secretary of the Navy Paul Hamilton sent Chauncey a cipher on September 1, 1812, just in case he needed to have secret communications with the Navy Department.

As you can imagine, given the era, this cipher was simple enough – appearing to be nothing more than a simple substitution cipher (i.e. one symbol replaces another, e.g., A=M).  Hamilton used all letters of the alphabet, a period, and then ten digits, numbers 1-9 ending with zero.  On top of each of these, he wrote in the cipher by hand.  This is easily breakable (as are presumably all simple substitute ciphers).

What Hamilton did, though, was use many of the lower row, i.e., plaintext, symbols as ciphers, in most cases simply writing them differently.  Since writing styles are different, this could easily lead to confusion.

For example, Hamilton used what appears to be a capital J to encipher p while the small j is enciphered with what looks like a v.  When writing back to Hamilton in code, Chauncey would presumably have had to write the symbols the exact same way that Hamilton wrote them if Hamilton were to understand a message. For his part, Hamilton did go to great lengths to avoid confusion.  For example, he also used easily written symbols, e.g., triangles and equal signs, to encipher.

By this time, cryptologists undoubtedly were long aware of the pitfall of handwritten ciphers and codes.  Good copying skills must have been essential, possible even an art in themselves.  Still, one wonders how serious a problem this was.  Do we know of incidents where a handwritten cipher was misread – with major ramifications – because it was not legible enough?  Today, of course, with modern technology, this type of situation is far less likely to happen.

For the record, there is no indication that this code was ever used by Chauncey.  He would prove to be a good commander, helping the Army capture both York (Toronto) and Fort George in the spring of 1813 and defeating the squadron of Commodore James L. Yeo in the “Burlington Races” in the fall.

The main source for this post, as well as the code, is the “The Pictorial Field-Book of the War of 1812.”  The original code, according to the field book, is in possession of the New York Historical Society.

Source: NSA