Great Fire of London Bacon Cipher

You have found this description of the Great Fire of London. You suspect it contains a secret message encrypted using Bacon’s Cipher.

Can you work out what it really says?

the great fire was an accident.baconcode

oN ThE SEconD Of

SEPTEmbeR, The KiNG’s


oF HIs ovEN sMOuLDeRiNG.


fiRewOOD Left nearby. three

hours later his bakery in

pudding lane was on fire. the

winds then spread the fire

across london.

To decrypt a message written using Bacon’s Cipher:

1. Break the message into groups of 5 letters removing

punctuation and spaces.

2. Remove groups of letters that are all lower case.

3. Write the message out 5 letters at a time replacing

capital letters with ‘a’ and lower case letters with ‘b’.

4. Look up each group of 5 ‘a’s and ‘b’s in turn (the

ciphertext) and write down the letter from the table

(the plaintext).

You may need to guess between I and J and U and V as

they are each treated as one letter.

For example, given the message:

            a poem: HelLO, WorLd

1. Break it in to groups of 5 letters:

            apoem HelLO WorLd

2. Remove groups that are all lower case:

              HelLO WorLd

3. Replace by ‘a’s and ‘b’s

              abbaa abbab

4. Look up the cipher text letter for each group of 5 in the table to get the message

               N      O

Download a printable copy of this puzzle

Download a printable solution

Cartoon Animal Eyes Under Big Stone

Scratch Bacon Encryption Program