As part of a crowdsourced project:
Volunteers are logging on — at decodingthecivilwar.org — to transcribe thousands of long-lost wartime missives using a crowdsourcing platform developed and managed, in part, by the University of Minnesota...
...in 2009, two wooden trunks holding 35 ledger and code books turned up and were sold at auction. The archive had been apparently been taken by Thomas T. Eckert, head of the Civil War telegraph program, when he left government service. With almost 16,000 messages, the telegram cache is so dense, so massive, that Einaudi predicted that it would take a full-time staff as long as a decade to painstakingly decipher the messages one by one.That’s where the crowdsourcing comes in...Starting this past June, volunteers from across the country have been able to register on the Decoding the Civil War website, take a quick tutorial and begin scrutinizing the scanned copies of the original telegrams.
Note this is not "codebreaking" per se - it's more a matter of deciphering sometimes-illegible handwriting.
Because the handwriting of the 1860s is filled with flourishes and quirks that have long passed from style, volunteers often debate the meaning of the scribblings on the website’s talk boards. “We have people online 24 hours a day,” Einaudi said. “When you increase the eyeballs, you increase consensus, the wisdom of the crowd.”..“We can’t build an algorithm that can do this kind of work,” said Lucy Fortson, U Zooniverse director. “Humans have developed this beautiful visual cortex that allows them to see complex patterns, distinguish visual information and type what they see.“Machines can do data analysis, but they aren’t any good at reading handwriting.”..“A certain type of person is predisposed to volunteering on a site like this. We see a hankering to be involved with something meaningful, and research translates as meaningful. With crowdsourcing, they have a bit of ownership in what we might find.”
If you're interested, here is the project's website.